First, look here: VNC FAQ: Ports. Since this question is a bit too technical for me, I asked a programmer friend of mine, Phil Hord, for help, and here's what he suggests:

The university may block all incoming services. If so, it doesn't matter what port you put it on; you won't be able to reach it unless she initiates the connection. You could probably have her PC connect to your PC all the time with ssh enabling port-forwarding. Since you can presumably control the firewall on your end, you can open up the requisite port for her to connect to and then configure the software to
allow it all to work.

For my configuration to work, I wound up creating a VPN to link my home and office PC's across several NATs and a vigorous corporate firewall. You can do something like that, but maybe you won't have to jump through as many hoops as I did. (Here's how:
My VPN traverses three firewalls)

You can use SSH to open up ports through whatever firewall she faces. You'll need an SSH server running on your end. She'll need to run ssh on her end. You might even be able to make it "always-on". I haven't experimented much with ssh clients on Linux. But it should be pretty easy.

Finally, if she ends up running Windows, she'll need to check out Hamachi or LogMeIn and if she's on a Mac system, the VNC package of choice is Chicken of the VNC.