Not a user of precompiled kernels or modules but I would think ALSA would be built into the precompiled rpm kernel rpms that are released. Alsa is part of the kernel itself. Install the new kernel and see if sound works fine. My only thought is maybe your hardware may not be part of the main stream.
Distribution: RHEL 5.1 with Pieces of this and that.
Kernel 18.104.22.168, KDE 3.5.8 and KDE 4.0 beta, Plus Development src.rpm, ATI fglrx64_7_1_0-8.433-1 rpm with 3D and DRI working.
Acer 5100-5840 with webcam, ati, sdcard reader, sound, atheros based wireless, all working. Only thing not working is the memory stick reader.