Pork sirloin roast

If it's been fully cured (smoked, then hung for a few months), it likely just needs to be warmed through for serving (or even just sliced).

If it's soft, you might need to cook it, and then you could roast it in the oven ... a crock pot might be okay; it's hard to say without having seen it.

But if it's quite firm, I'd likely just slice pieces off like you might other dry cured hams like Prosciutto, speck, jamón or country ham.

If it's heavily salted, I'd be more likely to use it as a flavoring than a meat -- cut off bits, and add to vegetable dishes when cooking. It goes great with dark greens or in bean dishes. (I just had an excellent bean & ham soup last night at a meeting that a few of us treat as a pot-luck)

I don't think a pork sirloin roast will stand up to that kind of cooking very well. That is a very lean piece of meat, which does not lend itself to long cooking times at low temperatures. That type of cooking is best reserved for cuts of meat with lots of fat and/or connective tissue. If you put a pork sirloin roast in your cooker for 8 hours on low, you're going to have one tough, dry piece of meat when you are through.

You would be better served by cooking it in the oven at higher heat, for a relatively short period of time, like 400F for an hour or so. Bear in mind, you're not going to get to a fall-apart tender state with a sirloin roast. This isn't a pork butt with which you're dealing, which you'd take up to an internal temperature of 195F or more. Rather, you're going to want to target the safe temperature, and no higher. You want the meat to be juicy. Cut into thinner slices to achieve maximum tenderness.