Forcing package removal via comps.xml?

[Toralf Lund <toralf@xxxxxxxxxxxxxx>]

Is there any way I can force specific packages to be removed on upgrade 
installation, via directives in comps.xml? Essentially, I want the 
effect of rpm "Obsoletes:", only I'd like pre-built packages to 
"obsolete" ones not mentioned there, and I'd rather not re-build the 
rpms if I can avoid it.

- Toralf