I tried adding http://chirp.danplanet.com/projects/chirp/repository
That's because that URL is a web interface to a SCM repository, not a repository of SuSE packages.
Is there another option?
Not for SuSE right now, no.
The reason I ask is that chirp fails to install under openSUSE 11.4 software manager yast2.
It complains that "nothing provides pyserial needed by chirp-0.1.1.12-1.noarch " even though I have the latest python-serial offered by yast2 (2.5-3.3).
That's because the RPMs are for RedHat/Fedora systems which have different package names for some things. You could try forcing the install, but it's likely that the Fedora RPM won't put things in the right place.
If you want to install on SuSE, you'll need to do so via a source install:
http://chirp.danplanet.com/projects/chirp/wiki/Running_Under_Linux#Manual-in...