Hello,
so, more or less, you need a skeleton of a device driver for autoconfig card, but you need to discover by yourself all the IDE registers (they are not much, just almost the possible combinations of five digits, in fact are four digits 2^4, three address lines and the chip-select signal).
For this task you need an oscilloscope, discover what are the three address lines and, with a disassembler, and a IDE device attached to the port (as master) try to send an IDE command like $90 (the LED of the IDE device will blink) with a base address as the card appear to (a tool like SysInfo show the base address of this card, but not the memory part, just the other one, so this card appear as two cards, if i am right); at this base address you need to add the address result from the combination of the three address line that go to the IDE port and discover the address of the Command Register.
This is the technic that i have in mind about your card.
You can read an ATA spec. doc. (named X3T9 and succ.) and the Gayle spec. about Amiga specific solution for IDE port then, specific for the registers, if you find into the net the spec. of the commercial IDE card BUDDHA, just to have more clear the scenery.
I have here, coded by my in assembler, a device driver for autoconfig card, made for an unreleased ZorroII IDE card (my own card for my A3000), so, with the address of all the ATA registers on hand, and a little bit of work, i see possible to build a driver for your card.
Tell me
Regards
Stefano