Comment 2 for bug 234323

You could have a wrapper around gksu or kdesu running one or the other depending on the current session; such a wrapper is provided in the menu package, but you don't want to pull that, it changes gnome menus.

The "update-manager" utility which is used in both KDE and GNOME in Ubuntu calls gksu; this is what I'd recommend for now with a dep on gksu.