Focus camera from computer

[wil3]

Hello. I am building a gel documentation system, and I need to be able to control/focus a digital camera while viewing its image field on a computer screen. I'm looking for an inexpensive program that can give a live feed of the view field of a digital camera(any brand will do), and that can adjust common settings like ISO/focus remotely.

It doesn't matter whether the camera is SLR or a point-and-shoot. This capability will determine what camera I buy.

Thanks very much.