WISH: Extending git commit --amend

Form current documentation

--amend

    Used to amend the tip of the current branch. Prepare the tree
object you would want to replace the latest commit as usual (this
includes the usual -i/-o and explicit paths), and the commit log
editor is seeded with the commit message from the tip of the current
branch. The commit you create replaces the current tip — if it was a
merge, it will have the parents of the current tip as parents — so the
current top commit is discarded.

    It is a rough equivalent for:

            $ git reset --soft HEAD^
            $ ... do something else to come up with the right tree ...
            $ git commit -c ORIG_HEAD

    but can be used to amend a merge commit.

I find myself wanting to amend not tip of the branch, but an older commit (typically to change log message). As example if I have this

D---E---F---G master

And I want to amend revision E currently I do

            $ git branch tmp
            $ git reset E
            $ git commit --amend
            $ git rebase tmp master
            $ git branch -d tmp

Would be possible to extend git commit --amend so to automate the above sequence ? Or does perhaps exists a better sequence to change (actually simulate the change of) log message of an inner revision?

Thanks in advance Marco