They say the x-rays won't hurt any "normal" film, I guess meaning anything from ISO 50 to 400. I ALWAYS have them hand inspect my film. If they tell me that I don't need to worry about my 100 speed, etc., I lie and tell them I "rate the film" at different speeds, so I might actually push this roll of 100 three stops so it will behave more like a high speed film, and that for that reason, it can get fogged by the machines. They usually don't know what I'm talking about and just go ahead and oblige my request.
Since 9-11, I've had my film hand inspected about 12 times; and no TSA person has ever flat-out refused. Most airports have a system where they swab it and put the swabs into a "bomb sniffer" unit.
Okay, so what about the film in your camera? Some older cameras can be rewound almost all the way, that is you can push the rewind button on the bottom and manually wind the thing until you hear the film come off the uptake reel. Then, you can reload the whole roll and just advance an extra picture to get to just beyond where you left off. This is hard with cameras with electric winders, and if your camera only runs on fully-automatic mode, it might be hard to get back to that picture you were on without having to reexpose the frames.
What I would recommend for 400 speed film (that's nice stuff, the CN, by the way), is to advance the film a few frames before you go through the xray. That way, all your exposed frames will be somewhat "protected" by throwaway frames. 2-3 shots should be okay. Take a picture of a lightbulb or something so they don't print it at the lab and charge you.
Then, when you get through the xray, shoot a couple more to get to fresh, unblemished film. This would be my Modus Operandi.
Glad to hear you're shooting film, by the way.