On my way to work I remembered this:
http://www.chiefdelphi.com/media/papers/1453
I wrote that a few years ago for rapid prototyping on the min-RC. We didn't have an RC radio for it so I wrote an app for the PC to provide a UI to drive the robot using the serial port. I don't know whether it will work with the Vex, but the RC code is pretty simple. It provides 4 2-axis joysticks (widgets you drive with the mouse) and 8 digital inputs. The robot can send back sensor data. It will also plot I/O channels for you.
If you can get a remote desktop or application sharing program to work over the internet then you could just remote into the laptop and drive it using that UI.