It's so easy to ask a question that's hard to answer in full detail. In a nutshell:
1. I think streaming between TiVo's has been implemented on the TiVo Premiere. (I don't have one.) Check out the Premiere forum on this site. But I don't believe this allows putting a copy on a PC.
2. For the TiVo HD the workaround involves both software and hardware hacking. I'll leave it to lrhorer to reply here telling you how straightforward that is and why he can't understand why anyone would hesitate to do it.
Discussion of actual technical details of hacking are verboten on this forum. There is another forum that discusses this but even the link to it automaticallly will be detected and blocked on this forum. I don't believe there is even a hacking solution for the Premiere yet.