Well I'm not sure what you're trying to do, so I can't suggest anything really.
I mean, if the rhel4 seemed to install OK, surely it should indicate what the "missing driver" is, by not doing something i.e. if it won't boot into graphic mode, then theres an graphic driver missing etc. It's my understanding that drivers are function/hardware specific.
Plus, surely it's not gonna have everything on the first CD ? i.e. that the installer would/should identify the attached hardware and install specific drivers for it (e.g. my mandriva 2006 powerpack install detected that my nvidia based graphics card, so, as it's the powerpack version that already has the nvidia driver available it installed it).
Perhaps you could elaborate what exactly your system is doing, or not as the case probably is, so that someone might read your post and be able to offer a more precise answer.