oh man, your so lucky! ive always wanted a snake problem so id have an excuse to get one of these http://www.gunblast.com/Taurus-Judge.htm
You know that would also be good because if its in the wall and you can only hear it but cant get to it..... well just blast the wall with one of those shot shells. (use bird shot tho, buck might reeealy tear up the room on the other side..
If you get one you will tell me how it works right?
(in all seriousness, good luck with that. There arent any snakes near my house so ive never delt with them, so i can only imagin how disconcerting that is.)