I'm using freebsd 6.2-RELEASE-p4 and coda-client-6.1.2 installed from ports.

  I run venus-setup fine. But when venus is executed, the kernel panics.
  Is there a working version for freebsd 6.2? Is there a user level
  client available?

I suspect that the kernel venus module needs fixing.  I recently made a
lot of changes to the kernel code in NetBSD, and it works well now
(netbsd-4 and current).  This is going to require significant vnode clue.