hmm, that's a tricky question. tags are not commits at all in git. just line in cvs.
git-cvsimport imports tags just fine.
i assume in svn you create a tag by copying the tree, but then the cvs2svn importscript seems to create another commit on top of that, making the tag effectively a branch.
maybe just not make that extra commit?
btw, is this cvs2svn script your own work or is it the same cvs2svn that comes from http://cvs2svn.tigris.org/ ?
the latter cvs2svn now also supports importing to git: http://www.nabble.com/cvs2svn-conversion-directly-to-git-ready-for-experimen...
doing that in combination with your scripts may be worth a try...
greetings, martin.