We have compiled and re-compiled kernels on 5.6 with no problem using various kernel source .rpm from RH7.3 updates mirrors on multiple 5.6 servers on various i386 CPUs.
We currently run 2.4.20-24.7 on several 5.6 servers (inluding smp + RAID1 + RAID5 support).
To install new kernel, dowload kernel source rpm from and RH updates mirror then:
* First, backup your /usr/src/linux*/.config file and rename your old /lib/modules/* folders.
* Next, "make mrproper" then "make menuconfig", then "make dep modules moules_install bzImage".
* Copy System map etc. to /boot/* as per normal and make sure to check/run lilo.
You need to patch kernel if running pptp but support for all the standard 5.6 stuff should work fine "out of the box".
I found that running "make mrproper" whenever you need to re-compile is the main trick (even though it should not really be necessary

R.