We've been running FB 1.0.x on SME 5.6 for over a year, as well as running FB on SME 6.0 for testing.
Other than having to create a custom template for /etc/hosts.allow, I just used the standard rpm.
We used the superserver rpm -- the classic server would require a /etc/xinetd.d custom template (I think, didn't try it myself).
The custom template was only necessary if you want to access FB for local network machines (which we did).
To get it working, I just copied and hacked up the mysql template, substituting FB where appropriate.