Help requested - trying to build a tool doing whole-tree commits

(Apologies if this arrives twice. I'm on the road, with somewhat flaky email.)

Because of my work on reposurgeon, I am sometimes asked to produce git repositories for very old projects that not only are still using CVS but have ancient releases not in the CVS repository, preserved only as tarballs. I have such a request currently pending from the robotfindskitten project.

To automate this process, I am trying to write a tool that will take a sequence of file trees and synthetic change comments in one end and emit a git repository composing them into a DAG out the other. The working name for this tool is 'gitpacker'.

I've already written the unpacking operation (git repo to tree sequence plus log). This morning I discovered that git-commit won't do quite what I need for the packing operation. I'm requesting help.

I need a command or command sequence that will commit an entire file tree to a repository...

(a) Allowing me to specify committer and author metadata, and

(b) deleting paths not present in the previous commit on the current branch, and

(c) allowing me to specify merge links from other previous commits.

git commit -a passes (a) and (b) but not (c).

Advice on how to accomplish this is requested

Advice on a better name for the tool is also requested, as I'm not happy with the way my use of 'pack' collides with existing git use of the same verb.