Rob,
I'm in the same boat. I just bought a used Proliant 6500 with no RAID controller. I put 5 hot swap 4.3GB SCSI drives in it and had to purchase separately a SmartArray 221 RAID controller (PCI.) I'm trying to install 6.0b2.
My Proliant detects the 221 at boot, but I cannot configure the RAID5 array without the SmartStart CD - none of the downloadable utilities worked. I had to purchase a copy of the CD from Compaq - $21 US (plus $20 US to ship to Canada via USPS standard - Unbelievable!!) I think Compaq should have these CDs available as ISO images from their website. It's annoying as hell to have to wait 7 - 10 days for it to arrive in the mail (and they won't expedite shipping, either.)
Since my CD hasn't arrived yet, I'm unable to determine whether or not this is going to work fine. In theory, once you set up your hardware RAID, you perform the SME installation for a single disk, and the hardware controller will do the rest. I don't believe that SME has anything to do with it if you're installing a hardware RAID.
For now, my startup shows that I have 1 logical drive configured, but also says there are no fixed disks. I'll try to update once I get the SmartStart CD. Oh, and if you order the CD, be very careful about which version you order - not all versions work with all models. I had to specify version 5.5 (as opposed to 6.x, which is their most current.)