Obviously, it depends on whether her laptop has a wireless adapter.
And you may have to make some changes to the networking setup on her computer to redirect the present use of (presumably) an internal dial modem instead to the wireless adapter. If wifi, you will have to supply your wireless security passphrase.
If no wireless adapter you will have to redirect her networking setting to connect via the ethernet port (if any) and connect that to your router via an ethernet cable.
Sounds like a lot of fuss but isn't that difficult if her machine is running XP or later -- though I'm a bit worried you may have a problem restoring settings that work when she takes the machine home again.
If earlier than XP, I'd definitely not use her computer.