I got those codes to work with different addresses for each tivo, but I still have an issue.
The remote address in the systems and information screen on the tivos is automatically reset to 0 if a regular tivo remote is used, or one that is not set to the custom address.

So if someone in my family grabs one of the other remotes and goes into that screen, the "custom" address will be reset. This would mess up my Q50 config. Tivo makes it WAY too easy to reset this address...
So I went ahead and decided to use IR blasters to each tivo and this way i won't have to worry about it.