git-archive and tar options

the git-archive manpage states:

"git archive [--format=<fmt>] [--list] [--prefix=<prefix>/] [<extra>] [-o 
| --output=<file>] [--worktree-attributes] [--remote=<repo> 
[--exec=<git-upload-archive>]] <tree-ish>  [path\u2026]

<extra>
    This can be any options that the archiver backend understands. See next 
section."

I have tar 1.23 and want to use the --transform option.  How can I feed 
git-archive additional tar options?

Working syntax starting points for git-archive and tar:

git archive --format=tar -o my.tar HEAD Web/Templates/
tar -cvf my.tar --transform 's,^Web/Templates/,myPath/myWeb/Templates/,' 
WebPortal/Templates/

Failed syntax attempts for feeding tar option to git-archive:

git archive --format=tar -o my.tar HEAD --transform 
's,^Web/Templates/,myPath/myWeb/Templates/,' WebPortal/Templates/
error: unknown option `transform'

git archive --format=tar -o my.tar --transform 
's,^Web/Templates/,myPath/myWeb/Templates/,' HEAD WebPortal/Templates/
error: unknown option `transform'


v/r,
neal