I have written little utilities in QB45 that poke various registers to enhanced state on other chipsets. it is pretty easy if there are no special procedures involved prior/after changing the register(s). in most cases you have an index port to choose what register to read/write and a data port for the actual data, or all is done via PCI configuration space which you can do in a similar manner, following the PCI configuration mechanism protocol on two special IO ports.

Well, what I'm looking at doing is possibly changing some registers in VIA chipsets to enable PC/PCI ports on certain motherboards. The south bridge has the capability, but I don't think it was enabled, so the pins that would handle GNT/REQ or Serial IRQ are instead disabled or assigned as GPIO pins.

I suppose this is a little above my ability, though.

If you only need to change the PCI registers you can use PCISET or SMB. Vendor ID should be 1106h and device ID 3227h and the registers controlling PC/PCI should be at offset 52h and 53h, but I'll guess you already found that in the datasheet.

Thanks, I'll try that out.