I'm really asking this on behalf of our sysadmins, so here goes:
We are moving from Serena to Team Foundation Server as our source code repository. It's a done deal (for better or worse) and I'm already aware of "no keyword expansion".
Anyway, the admins are planning to import source as version 1.0 (or whatever it uses for the first one) and forget about the history in Serena. However, it's a very large and fairly old codebase, and the loss of version history means losing a lot of information.
I have a fallback position of generating an ASCII version history files, one per module, and trying to attach them to each module in TFS. I'd much rather find a way to slam the version history in and preserve the version numbering (or something like it) once we're in TFS.
[Not answering the asked question] There's a CodePlex project out there that inserts keyword expansion to the TFS check-in process if you really want it. We use this with our SQL & PowerBuilder code and it seems to work well if you can accept a particular idiosyncrasy.
The project is Log Substitution Policy