Little thread resurrection here but, I've just installed a Sil3112 based card and moved my OSx86 installed disc from the ICH9R SATA port to the Sil3112 port because I want to boot my RAID'd XP install off the Intel controller.
All well and good, card installed and BIOS flashed to the base ROM, OSx86 disc detected. Created chain0, edited my boot.ini and viola I can select OSx86 and the Darwin boot loader fires up and starts to boot Leopard.

...until it tries to find a driver for the Sil3112, and hangs on the "Still waiting for root disk" prompt
Common Sense mentioned the AppleVIAATA.kext file and doing some device ID edits in there, but I haven't got a clue what I'm looking for - any ideas?
edit - Just put the OSx86 disk back onto the Intel controller to boot it, edited the PCI ID (added 0x31121095 to the end of the list of VIA SATA controllers) and rebooted with it back on the Sil3112 controller. Same thing sadly.
Cheers in advance!