If you weren't looking for drivers for Windows 8, the answer would be simple. Intel does not list any IRST drivers for Windows 8 for the ICH10R that I can see.
A quick FYI, Windows 8 has its own new AHCI driver, storahci. I would suggest installing Windows 8 in AHCI mode, and just let this default driver load. But, it might not be compatible, Win 8 is new and not much information about it is available.
FYI, any Intel IRST RAID driver works fine as an AHCI driver, and does not need to be set to RAID mode to use, mode as the SATA mode is fine. TRIM is also not an issue at all, in contrast to what some think, TRIM works fine in RAID (called pass-through for single SSDs), AHCI, and IDE mode, as Intel has confirmed in the past. TRIM commands are issued by the Windows NTFS file system, not from the SATA driver. Some third part SATA chipsets/drivers may not pass TRIM, but Intel IRST and MS drivers with Intel SATA chipsets are fine.
The ICH10R was also used with the X58 chipset boards, and I have (or had) an X58 and G45 board, using the ICH10R. For the few remaining 4 series chipset boards Intel suggests this version of IRST:
http://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&DwnldID=15251&lang=eng&OSVersion=Windows%207%20%2864-bit%29*&DownloadType=
I've used later versions of IRST than that one on my G45/ICH10R board, such as the one listed for X58 boards:
http://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&DwnldID=20868&lang=eng&OSVersion=Windows%207%20%2864-bit%29*&DownloadType=
I would suggest the IRST 11 driver to try with Windows 8. Microsoft is doing things differently (strangely) with Windows 8, in the past they have provided a tool to check the PC for compatibility with their new OS, like Windows 7 or Vista. MS did not do that for Windows 8, all they have is a database with entries provided by users that is supposed to indicate what software and hardware works with it or does not work. PC builders are unhappy with some board manufactures that are not listing drivers for Windows 8 that work with their boards. I imagine you are one of those too?
The latest Windows 8 IRST driver (second one released) is this:
http://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&DwnldID=22272&lang=eng&OSVersion=Windows%208%2C%2064-bit*&DownloadType=
I strongly suggest you read the Readme file on that page, regarding the requirements for that driver, such as specific versions of MS .NET framework. The corresponding chipset (inf file) installer is:
Download Center
The chipset files are difficult to specifically recommend. If you go with the Windows 8 IRST, you should use that installer. Actually, it might be best to first run the chipset file installer on your boards download page, and then run this one, which should update it as necessary.
With an older platform like yours, there are no guarantees about what will work. Windows 8 is new, MS is not helping much at all, so if you go beyond anything but the standard installation on older hardware, you are pretty much on your own.
