mac os x server is way better than mac os 9. consider yourself lucky...
anyway, you need to use the pdisk utility. it should be on the server install disk.
basically, os x server installs with three partitions, mosx_booter, a secondary bootloader, and the root ufs volume. you need to boot from the cd and use pdisk to delete all three partitions and create a new hfs partition in their place. then boot from the os 9 cd and initialize your newly created volume and install.
i strongly suggest that you try out os x server, it's a pretty nice os.
also, you might be able to boot into single user mode in os x server and use pdisk from there. i don't know, i've never tried that way. i believe holding down 's' will drop you into single user mode.
unless you have a separate hfs+ volume with important stuff, you can always reinitialize the whole disc. that's probably the easiest way.
or, if you have a separate hfs+ volume, you can dual boot. all you need is the system disk utility.
[This message has been edited by nibs (edited 12-01-2000).]