I have two UltraSparc II's. One running Redhat and one running Solaris 9. I use gcc instead of cc. You can get it here.
http://www.sunfreeware.com/
The hardest part was getting gcc to complie but the above link will guide you in the right direction.
I have had successful builds with the eqemu .5.0 source on my solaris box (9-30-2003) but have not been able to complie the latest source (as of 10-7-2003) under windows, linux or solaris. I usually wait until I get a good complie under windows, then complie under linux, debug and then complie under solaris and debug.
If you are using cc I can't help you. I've had too many problems compiling with cc.
Other sites:
http://www.ultralinux.org/