Gave up on trying to get Pata to work but.....
Got Sata to work on 2 motherboards (TUL TRS690-M1 & MSI K9A2 Platinum) with SB600 chipset!!
The key was to delete all of the other AMD storage ahci.o entries and just add the 1002:4380 0000:0000 storage ahci.o to simple.map.
I followed these instructions http://www.vm-help.com/esx40i/customize_oem_tgz.php#Example
, but didn't need to do steps 7-9:
7) cp /etc/vmware/pci.ids pci.ids
8) vi pci.ids
-- add the necessary description for your devices (this will be displayed in the console and VI Client)
9) close vi - press ESC and enter :wq
Now I can reboot and my Datastores and VMs show up without having to run the vmkload_mod ahci script.
Thanks for your help.