can you use remote desktop from campus to access a computer that is behind a router offcampus? If so, what would be the steps to doing such?

Yes. You have to configure your router to forward the ports that Remote Desktop uses to point to the computer behind the router. The steps vary by make and model of router. Use Google.

Some even support DynaDNS.org's services. That is what I use over the summer when I'm traveling to get to my computer at home. I just RD to a Domain name and poof. You still need to establish port forwarding though.