So... you haven't tried the *GLX* *tarball*
, have you.
Use it instead of the GLX RPM.
Don't use only the kernel RPM -- as you found out, it doesn't work with your kernel. The 3123 kernel tarball should work with any kernel (except RH9's).
Then, rather than forcing the old kernel RPM to install, just to get the GLX RPM to install, skip that entire process and just use the GLX tarball. This one: