Hi, I have been wanting to hackintosh for ages, but its taken me a while to get my PC nice and stable, its a self build and had issues with an old power supply, so I am quite a noob really. Having said that I have gleaned a lot of information from where I can.
Mmmmm, the GTX295 is an interesting card, not read much about this beast to be honest, it does say in some blurb that it is "like" SLI, whether that gets you past the no SLI on mac I do not know, am sure the card will show up, If my custom GTX470 can.
SL is Snow leopard and ML is Mountain LIon, it is something that had me wondering as well, not to be confused with S/L/E which is the path on the root of your HD to the system/library/extensions folder.....
If I can help, just shout.
I have written a full step by step guide at the end of my post here on how I got fully functioning Snow leopard 10.6.8
The way I got my GTX 470 to work properly was to edit the AGPM kext, copy it to your desktop, find out what your computer is listed as, either mac mini or mac pro or whatever, find this in the long list of devices within the plist, then edit the device vendor id to match your card on one of the listings, if your mac mini or mac pro or whatever is not listed then edit an existing one to what your system profiler states that you have, now in the AGPM are a load of power states, many of them refer to NVIDIA cards, and so can be changed quite easilly to match an NVIDIA card, not sure what to do with AMD but then there are MACS with AMD cards too. Check the device vendors in the list to see if any are AMD and use that one for your amendments. Edit using text editor then save, then drag and drop the kext onto "Kext Utility" available on #####. Then fix permissions on disk.
Also of course I installed cuda drivers, rebooted and then manually installed nvidia drivers for mac from their driver package.
Then I used Chamelon Wizard to update the bootloader on the boot drive to its latest version, using the download option, after this and after setting GraphicsEnabler=Yes, "Graphics Mode"="1920x1080x32@60" then my GTX470 showed up listed as a GTX470 with 1280mb of VRAM.
The combination of the two seemed to get everything working ok, but this was on Snow Leopard.
So step by step....
Open S/L/E then find AGPM kext, highlight it, right click, copy and save to your desktop.
Once there, right click again and click, show package contents.
Then open the Plist.info version file or something using text editor.
Find within the long list the heading that matches your mac mini or mac pro or imac or whatever.
Alter the device vendor ID to whatever you have, check system profiler, if it says 0x06cd like mine does then you just need to insert the 06cd at the end where it says device vendor, AMD may be different.
These low and high thresholds are the shifts in power states that a NVIDIA Gpu has, these I altered to suit my card after finding a post on a GTX470.
Save the plist once completed, basically, your device vendor ID and the computer type in the AGPM should match your own system.
Drag and drop the kext onto Kext utility, let it run.
Open Chameleon wizard, install new bootloader with latest downloaded version.