I have edited the step-by-step installation guide for NAV 3.0 on Red Hat Enterprise Linux 4 to cover the RC2 version. You can find it here:
http://metanav.ntnu.no/moin.cgi/InstallingOnRHEL4
Please give me feedback when you find errors or omissions so I can fix them. Or if you just want to comment it... :-)
I hope this can be of help for someone.
Regards, Roger