It is indeed possible to do this. Read up the thread and you'll see Rob's response...he maintains the following site that tells you in great detail how to go about it:

http://www.hifi-remote.com/

I haven't completed the operation yet, but have gotten to the point of interfacing my 1050 remote w/my PC (using the connector cable sold on the site) and downloading all the information from the remote into the computer. It's pretty cool when your PC suddenly pops up with all the codes from your remote! I haven't yet uploaded the Tivo codes on the JP1 site. But it looks like this is pretty straightforward. Give it a shot, it's fun.