Theres a topic on system requirements, which says:
RHEL 32-bit ES/AS 4.0-Update 7 or 32-bit ES/AS 5.0-Update 3 (Minimal and Full Install)
So that's what's supported. If you manage to get it working on 6, it won't be supported, as in, if you call JTAC with a problem, I'd be very surprised if they helped you until you got on a supported os.
(if my post helped solve your problem, mark it as accepted solution)