Has been answered before in this thread :
You may be out of luck on an oldish RHEL 5, should be OK on EL 6.3.
The example says Fedora : RHEL 6 is Fedora 12 based. RHEL 5 : The old Fedora 6.
You may have a chance with RHEL5, latest kernel ..
Update the kernel : # yum install kernel
And a very good Ubuntu example, MTS ..
( Not much difference on any Gnome version, any OS.)