Michael (and the rpm.livna.org maintainer), please see my brand-new HOWTO on this topic:
http://tldp.org/HOWTO/Fedora-Multimedia-Installation-HOWTO/index.html
I found I had to add freshrpms in order to get apt. I needed apt in order to get jre RPMs from Dag Wieers's repository.
I would actually like to recommend livna only in my HOWTO, but there are things it lacks. If livna wants to be the one-stop shop for everything proprietary and patented that isn't in Fedora Core (which is where it seems to be heading, and I heartily approve), then it needs to carry the following:
Java jre RPMs (see Dag Wieers's repostory) mame and mame ROM RPMs
XMame is totally free and legal, isn't it ? Mame ROMS are illegal though, and not only in the US (this is not a software patent problem).
RealPlayer RPMs (see http://cambuca.ldhs.cetuc.puc-rio.br/xine/) Win32 binary-codec RPMs to be used with mplayer
How about Flash plugin and libdvdcss ?