Incremental cvsimports

Dear Git,

I have a 3Gb repository (10 years of history) which I want to import into git.

I have tested little pieces of that and a 23Mb directory expands to 120Mb prior
to packing/pruning.  Therefore I don't have a big enough disk to import the
whole repository at once. So I figure I could do it in pieces with a pack after
each piece.

So I tried something like:

 1.      $ git cvsimport  -o austrics -v -d /cvsroot -C /GitRepo /cvsroot/A

followed by

 2.     $ git cvsimport  -o austrics -v -d /cvsroot -C /GitRepo /cvsroot/B

After 1, /GitRepo/.git is set up but /GitRepo has the members of A,
not A itself.
After 2, /GitRepo also has members of B. This isn't quite what I wanted!

Is there a way to do this?

Cheers,
Geoff Russell