If there isn't a framebuilder or class nearby, check the Experimental Aircaft Association website for aircraft welding classes. They move 'em around the country and we use chome-moly tubing in many designs. Other than a different structure and that we don't really use butted tubing for planes, the training applies both ways.
Also, if you're marketably skilled at bike frame welding, you'll be able to work on airframes as well (experimentals, though, unless you're working under an A&P mechanic or for an FAA approved Repair Station).

Oxy-Aceteline is a real popular method with us, too, though other methods are used.