As Fedora testers know, system-config-packages is retired and replaced by Pirut. That new frontend package manager share some look to its predecessor. The major different is the use of yum as backend.
Currently still in early development, I tested Pirut with the inclusion of Freshrpms, a third party repository. Interestingly, Pirut is able to detect these third parties pacakge when setting in list mode. Unfortunately, Pirut won't let user to select the same packages to install under browser mode. It lloks like some yum command needs to be sorted out.