I say suck it up, buddy. Lame or not, you aparently broke a rule. I'm not trying to be a wank or anything, but I'd expect the very same thing if I didn't play nice (it is someone else's playground afterall).
Since boards use a username and password, that's what your banning is most likely based upon. Like I can log into my OC'rs account from any computer I can get my hands on, at any location, any IP.
So instead of trying to get in the back door (for which you'll probably get slapped down as soon as you login), try e-mailing a site admin and humbly beg using your sweetest vernacular to get your PM's forwarded via e-mail.
If you're banned for life, well...live and learn.
*BTW, changing IP is only usefull if you're going to start a new account...at which point you won't be able to get the PM's of your other persona anyway.