Read this thread at photo.net. I've read Ilford's report on the test with paper somewhere but I can't find it anymore. I hand carry my paper in a plastic bag and have it go through the carry-on luggage scanner. Works fine.
You can try the mail route. I've mail ordered paper from the US to Canada and I'm pretty sure it went on a plane. The paper was fine on arrival. Ask your sister to mail you a small (cheap) pack of paper and test it when it arrives. If its fogged than there's no big loss.