ATI PC Cards in MacPro???????

Really new to this and do not know if this is right place to post. Looking for any and all info. on using the 4850 and 4870 PC cards in a Pro. I have looked for a long time reading different forums, a lot of them outdated. Just when I get on the trail in a forum, someone jumps in with their problem and just derails everything. A lot of the links have been removed and so on. Trying to find the mac roms. for some of these cards. Any help at all will be appreciated, Thanks

Yeah, I googled, Binged, yahooed, metacrawlered, and just came up with basically the same links over and over no matter how I worded it. Unless somebody has a different way to search.

Great. Thanks for that. I know for a lot of you guys on here that have genius IO's it is simple to do, a lot of the terminology is a foreign language to guys like me. I have looked at a lot of posts in a lot of forums, downloaded ATI flasher, Win flash, Freya,(which, when finished looks to be pretty slick), and some roms, but trying to isolate one method, without error seems daunting. I can try the posted method and see. I would be a lot more comfortable with one post that says:
1. Do ABC,then
2. Do XYZ, then
3. You are done
Thought I had a lead on a simple way, then realized it was a Hackintosh forum. So, thanks for the help, and any future suggestions you may have

Before you replied, I took a Sapphire 4850, stuck it in slot 1 of the MacPro 1.1, installed; ATI Package.pkg, version 1, and installed; Enabler_for_Nvidia_and_multiple_ATI_cards.pkg
This allowed the 4850 to be recognized in System Profiler with this:
Chipset Model: ATI Radeon HD 4850
Type: GPU
Bus: PCIe
Slot: Slot-1
PCIe Lane Width: x16
Vendor: ATI (0x1002)
Device ID: 0x9442
Revision ID: 0x0000
ROM Revision ID 113-B1480A-236
EFI Driver Revision: 01.00.236
Displays:
Display connector:
Display connector:

Showing no display connected I guess????

Tried hooking up monitor--black screen..........but it showed up in System Profiler
Any ideas before i try your latest suggestion??

Just took a quick peek at what you posted and I downloaded---Freakin' awesome!!!!!!!

Well, followed your guidance step by step and I have success with the ATI 4870 512mb card. I about stroked out though, when I hooked up the monitor, booted,
got the boot screen and then the screen went black! I switched the monitor to the other DVI connector on the card and the screen came up-YAHOOOO!!! Put an empty DVI-VGA adapter in the connection closest the logic board, and then stuck the monitor on the outside connection--success,,again!!!! You rock!!! And it will also work in the PC I have been using. Couldn't be happier,, Thank you
Will this work the 4850 cards??????????????