if you want to take it on an airline, you have to remove any fuel residue as it will set off bomb detectors. this means a full teardown and cleaning of your cars. flushing out the engines with ARO, and leaving your fuel tanks and lines at home. buy new tanks and lines where ever your going, and when done, leave them there, or mail them home. i would pack all your gear in 1 bag, clothes in the 2nd, and put car and radio in your carry on. also bring along some rc mags, so if there is question its easier explained.
as diver said the easiest thing to do, is ship the car and gear where ever your going. but if you can't, do as i said above and you should have minimal problems. its the method that all the pros use when traveling with thier cars. (they have a discussion on this very topic on another forum i read)