Use 1/4 inch copper tubing with a compression needle valve to run propane to a gas light

I don't think it's as dire as all the comments are making it out to be. Some people are just afraid of gas, just like some people are afraid of anything involving electricity. If you think it's just a loose coupling, you can turn the gas off, unscrew the coupling, apply pipe dope (not tape) and re-attach the coupling and turn the gas back on. If it still smells you aren't any worse off than before minus a few bucks for the can of pipe dope.

The short answer is all you need is a new orifice.

The complicated answer is : don't do that. Ventless systems have been banned in various places, and come with significant hazards not fully mitigated by a carbon monoxide detector. Read for instance : http://www.energyvanguard.com/blog-building-science-HERS-BPI/bid/48762/Bob-Vila-and-the-Vent-Free-Gas-Fireplace-A-Sorry-State-of-Affairs

A choice quote: "After doing research, we decided we would never put a vent-free (room vented) appliance into our home. Because of this decision, we didn't believe it would be right to sell them to our customers."

I would suggest asking a different question "how can I vent this ventless gas log set?". You could also calculate the number of heating days : if this is just decoration perhaps it's cheaper to just run it on propane until it dies.