The default port is 3869 IIRC, personally I use 1024 - don't ask why...
I don't run 10.5 so I shoot a little in the dark with Leopard users but the steps on a 10.4 box would be to open up a port manually through the firewall: system prefs/sharing/firewall and create the new exception.
port name is other in drop down menu, tcp is 1024 or whatever you choose, UDP leave blank, assign description Firefly. You've shortened the name firefly assigns which is correct - known bug - now fire her up. Start server, let it run a while & if it seems to hang then yep - known bug... Give it a couple of minutes or more the stop & restart the server - it should now work & you'll be able to access the config and change other settings etc etc.
When you mentioned you couldn't install the preference pane, what did you mean? Just that or that you couldn't get beyond the hanging startup screen. If the former, then uninstall/reinstall with svn 1586
http://nightlies.fireflymediaserver.org ... n=svn-1586
... if the latter then hopefully doing the steps above will see you right.
good luck! andy
G5, OS X 10.5.8, 3 x M1000, iTunes 10.4, slimserver 6.2.1/alienbbc (now redundant), firefly svn 1586, uNSLUng 6.8