Hello Matt, welcome to the board.
I can’t speak for the Antarctic programs of other countries, so what I say here applies only to the US program… And what I say on this topic is based solely on what other people have told me, so take it with a grain of salt.
If you’re allowed to work in the US (I believe this means having a ‘green card’) then it should be no problem to apply to RPSC and possibly get a job. I’ve heard that if they really want someone who is not a US national, they’ll sometimes help them get the card — but it probably has to be a situation where they absolutely must have you for some reason. (It would help if you’re a doctor.) Lately they’ve been hiring Kiwis and Aussies to fill some some vacant positions, so it’s possible they might hire a Canadian as well. Perhaps give it a try?
The other option is to start contacting science groups to see if they need volunteer help. Again, it would help if you had some skill they needed, especially in the sciences. But I don’t think they have any restrictions on who (or what nationality) they bring with them. On the NSF (National Science Foundation) website is a list of most of the funded projects for the upcoming year, with descriptions of each event and contact information. The rest is up to you.
good luck,
glenn