I authored the G2 project, a friendly environment for the command line git lover.
Please get the project from github - G2 https://github.com/orefalo/g2
It has a bunch of handy commands, one of them being exactly what your are looking for: freeze
freeze - Freeze all files in the repository (additions, deletions, modifications) to the staging area, thus staging that content for inclusion in the next commit. Also accept a specific path as parameter