Hi [lots of numbers],
You can definitely have multiple Slingboxes on the same LAN. That's no problem at all.
Setup and local viewing works the same way, you'll just need to select your Slingbox in the directory. Your Slingbox and your roommate's will both show up.
For remote viewing, it's a bit different. Slingbox uses port 5001 as it's default internet streaming port. That's fine on the LAN with multiple Slingboxes, but each will need a different port assignment in order for remote viewing to work. Your router also needs a port forwarding rule for each Port/Slingbox.
That stuff is all covered when you run the setup assistant.
Hope this helps,