Yes you can create sourdough from regular yeast, but it's not necessary. Ordinary flour comes with a trace of yeast. In the San Francisco area, that yeast is famed. Just mix flour and water 50/50 to make a batter-like mixture and leave it in a jar on the counter. Put a lightly fitting lid on the jar.
Add more flour and water every 12h (give or take). You should be doubling the initial amount each time, so 1 teaspoon, 2 teaspoons, 4...
After a couple of days you'll see bubbles developing in the sourdough. Once you're at that stage, you can reduce the amount of care. 'Refresh' the sourdough once a week: mix, take out 1/2 of the sourdough, add the same amount back (50/50 flour/water as before), mix. According to the Wikipedia, this can be kept at room temperature.
Sourdough is a mixture of flour, water, yeast and bacteria. When unattended for some time, 'water' forms at the surface. This liquid contains some alcohol that adds to the flavor of the dough. It's part of the sourdough and should be mixed in when refreshing the dough.
You might want to try a desem starter. Have a look at the desem primer, which is also linked on the Wikipedia page. Starter instructions are given toward the end. Common lore says that desem starter should never get above 65F, which sounds perfect for your situation. (It's actually fine if it gets warmer than that, though.) Traditional conditions for creating a starter are 50-65F, and I imagine you must have an area at least in that temperature range. I don't think the high altitude should be an issue in getting a starter going, and it might actually help in the case of desem starter by allowing the internal sponge to grow slightly easier.
Basically, it's a dry dough sourdough starter -- different from the typical goupy or soupy sourdough starter most people work with. You begin a starter by essentially taking a little water and kneading in about as much whole grain flour as is reasonable to make a very dry little dough ball. (Whole wheat is traditional, but you can use other grains -- rye would probably be effective, but it's not traditional "desem.") Then bury it in flour. Standard practice is to throw half away every 24 hours and then add water and flour to repeat. You can also start with a very small amount and gradually enlarge the ball.
Eventually, you'll pull the ball out one day and it will be very soft and spongy inside. This will probably happen in about a week at low temperatures, but it could take more or less. At this point, I would usually do a few feedings 12 hours apart before using it to bake bread. If you want to ensure the strongest starter, I'd also do regular feedings for a few more days to really get the culture established.
You can easily convert a desem starter to a wetter version once it is established. Just add water to get the texture you want, and feed according to whatever starter recipe you want to follow.
And, of course, you can use to bake other kinds of bread. You can also convert it to another type of flour once established.
Why does this work better at lower temperatures? I've never actually tried it at very low temperatures (I've had success with a temp of 65F or so), but lots of people have. I think you might be able to get a more standard wet sourdough culture going with at least 50F temperatures -- I only recommend the desem method because anecdotally it's what a lot of people use at lower temperatures.
If it does work better, I assume it might have something to do with the way yeast and bacteria growth rates change at lower temperatures. Both are integral to a sourdough culture, but too much of one and not enough of the other, and the starter can fail. Early on in the creation of a starter, bacteria are much more active than yeast, and they produce a lot of byproducts, including acids which provide souring. In the first few days, you often end up with an excess of acetic acid (partly from bacteria that are undesirable and ultimately die off in the starter process), whereas a mature starter should produce more lactic acid. Excess acetic acid is known to be a significant inhibitor of yeast growth. So, at lower temperatures, the yeast may grow too slow and not have a chance to get established at all if there's too much acetic acid around. The high flour proportion in the desem starter could dilute the effect of all that acetic acid early on more effectively than in a wet starter. At least, that's what I'd theorize.
Regardless of the science, lots of people have success with the desem starter technique at lower temperatures. If you don't like maintaining that type of starter (which I personally have grown to like, because it seems to stay fresh longer with fewer feedings in the fridge once established), you can add more water once the starter is established.
As for allowing your dough to rise once you start baking, there are lots of ways to make a temporary humid warm space. If you have some small enclosed space that doesn't allow a lot of air circulation outside (microwave, small oven, etc.), put the dough in there along with a cup of hot water. Refresh the hot water as necessary to keep the desired temperature. If you don't have such a space, you can even take a large wider-than-tall cardboard box, cut off the top flaps, seal the bottom with packing tape, and invert it over your dough along with the cup of hot water. I used such makeshift proofing boxes for years until I actually was given a proofing box as a gift.
Frankly, you can let sourdough bread rise at lower temperatures, too, which will increase certain flavor elements. It will just take longer, and sometimes you might need to use a different amount of starter in the recipe so as not to end up with a loaf that's too sour in the end. But that will depend on the recipe and the specific characteristics of your mature starter.
Best Answer
The vinegar smell is an indicator that your sourdough is growing up in a too cold environment. Without diving into the details of the various lactobacillae found in the average sourdough cultures, the simple rule is that a cooler environment favors the strains that produce more acetic acid while warmer temperatures are better for the production of lactic acid - the former being the acid in vinegar and the latter the much milder acid known from fermented milk products.
As immediate measure, find a warmer place for you starter. Caveat: warmer temperatures will also mean more yeast activity, i.e. more bubbles and in the worst case, a tendency to creep out of the container, so leave enough room just to be sure.
The separation of layers is a sign that the microorganisms in your sourdough are starving - which can coincidally favour the slightly more robust acetic acid producing strains. Once your starter has been somewhat established, meaning you get a reliable activity after each feed, it’s better to learn from your dough which feeding cycle works best. Remember that feeding simply means supplying a certain number of microorganisms with food so that they can multiply. Warmer temperatures will also increase their growth rates, so you should take that into account.
Depending on the ratio of (starter) : (flour and water), feeding time can be every few hours or once every day and a half. Ideally you start with a chosen ratio and measure the time until it just starts to collapse again. This is the ideal feeding time. (measuring means you don’t have to rely on visual clues alone, but get an idea when to plan the next feeding.) If you have a very active starter, you’ll probably want to reduce the amount of starter for a given amount of flour and thus extend times between feedings. Do not go below 10% of starter or you risk spoiling: There won’t be enough sourdough microorganisms to keep the nasty kinds in check for sure.