Update - I'm in Penang now and have had a roll processed. The negs look Ok with no funny lines. The prints they gave me have colour casts, but I would put that down to average scanning. I think I am satisfied to keep shooting.
While I am here, is there any more risk with pushed films? I plan to go to some markets tonight and want to push some HP5 to 1600.
if you can, carry the film on your person(like in pockets) if possible. A friend of mine does that, and goes through the metal detector machine w/o any delays, most of the time ;)
Use an x-ray bag. There really easy to buy. If that's not enough, ask for what I call "the cotton swab treatment", aka a hand check. However, don't ask for this in Canada, because they insist on opening the back door of the camera.
Two times is not a problem as long as the ISO in less than 800. I do not have experience with ISO 800 film and x-rays. I have not had problems with ISO 400 film and multiple trips through the airport.