Creating software for chip reprogramming via usb

Just curious if anyone has any experience with this? Seems more a software programming question than an actual PIC question. We have simple functions to be altered in a circuit once assembled. For instance, a simple variable with either 1X, 2X, or 3X for the output. Just would be easier to have the software on my PDA or something and make simple changes and rewrite rather than using other bulky hardware systems.

If it's just variables then simply store them in the EEPROM.

Mike.

Yes, we were going to use the EEPROM for the variables. I think we just have a large knowledge gap to learn how to edit the EEPROM without a separate hardware piece if that is even possible.