Appreciate the google comment.
RedEyez: fglrx (catalyst) needs msi enabled in the kernel. So you need to build a custom kernel.
fglrx does not install with the 2.6.29 or 2.6.30 kernels. I tried two 2.2.28 kernels and had problems (not fglrx related) so for running fglrx I am sticking to 2.6.27 kernel. Some people have patched the code to allow compilation but I think they still have problems. So unless you have to have higher than 2.6.27, for now I would stick with the latest 2.6.27 kernel you can download.
You might need pci slot detection.
Power management options --->[*] ACPI (Advanced Configuration and Power Interface) Support --->
<*> PCI slot detection driver
You must enable msi in the Bus Options section.
Bus options (PCI etc.) ---> [*] Message Signaled Interrupts (MSI and MSI-X)
I can't remember if needed but I also enable
[*] Enable deprecated pci_find_* API
You also might be able to try the open source drivers (xf86-video-ati or xf86-video-radeonhd). 3D is not working yet for any of the newer hardware though. The latest of slackware-current comes with a reasonably recent stable versions of these. If you must use 2.6.29 or 2.6.30 then stick with these but you will not have any fast 3D with modern hardware (HD series for example).