I've never seen webmin, but...
It seems most folks who are talking about webmin are talking about very specific changes -- disk quotas, etc. Why not use webmin to make the changes, figure out what they are, and then make templates for those files and write some panels to do the work from e-smith manager? Using webmin this way would take some of the "guru" factor out of determining what/how to change, and allow some otherwise competent folks who are not Linux experts to focus on doing the web panels for e-smith.
Just a thought.