What do I have to do to add support for the VX-2R? I suspect I could edit the VX-3 code, or could somebody tell me if it Just Works anyway? I have read the list archives (and most of the main chirp_users list) but no mention is made of this radio. Google doesn't tell me much either.
As Rick said, start with the VX7 driver. The clone bits should mostly be correct, with the exception of the length of the last block. From there, you'll need to change the memory format to match that of the VX-2, which will almost definitely use different offsets for the start of the memory channels, and likely have a few other differences in the format itself.
The first thing to do is make a vx2 driver out of the vx-7 so that it shows up on its own in the UI. Then make sure you can clone out of the radio to it and determine the proper length of the final block. Then you should be able to save the image, even though the parsing code will choke on the actual contents.
Looking at the image with a hex editor, you should be able to determine where your first memory channel is, by looking for the BCD-encoded frequency. Adjust the offset of the start of the memory channel list and things should start to come into view. Once you have it aligned like that, you can start using the "show raw memory" function in the UI (right click on the channel to get it) and speed up the decoding process quite a bit.
I generally use Linux, and I am comfortable with Python. I have one VX-2R, and I don't want to break it..., but having said that I am building my own interface cable by hacking an FTDI-based USB->serial adaptor. All I have to do is remove the RS232 level shifter chip and connect VCCIO on the FTDI chip to 3V3 instead of 5V. Naturally I am doing all of this in my copious free time, so who knows when it will be finished.
You won't break the radio, although you might have to erase the memory a couple times before you get it right. I've never bricked a radio. It sounds like you've got the right skills to do this, so dive in and ask more questions :)
Thanks!