Integrating with hooks

I've created some bash functions which handle tagging some files with revision information, but even after reading the git manual I'm not really sure how to integrate them so that they remove revision expansion before each check-in (to avoid cluttering the repository with keyword substitutions), and add them back (with the current commit info) after each commit.

These are the functions:

    # Show some kind of useful revision string, like the RCS $Id$ string. I
    # think commit hash, filename, hostname containing the repository, and
    # timestamp should be plenty of information to track down a given file.
    git-id () {
	for file in "$@"; do
	    _date=$(date +'%F %T %Z')
	    git log -1 \
		--pretty=format:"[%h] \"$file\" $(hostname -f) ($_date)" \
		"$file"
	done
    }
    # Replace the $Id$ keyword string in the file itself.
    git-export () {
	for file in "$@"; do
	    echo Modifying $file...
	    _id=$(git-id "$file")
	    sed -ri 's/\$(Id|Revision).*\$/$Id: '"$_id"' $/' "$file"
	done
    }
    # Clean the $Id$ keyword string to prevent cluttering the repository
    # with keyword-revision diffs when we check the file back in.
    git-unexport () {
	for file in "$@"; do
	    echo Resetting $file...
	    sed -ri 's/\$Id.*\$/$Id$/' "$file"
	done
    }

How do I hook this in the way I want so that it's handled automatically?