Windows 7: AHCI will not load during install

I am using the latest extracted Intel Matrix and INF install drivers and no matter what I try Windows 7 Ultimate (x64) will not load the AHCI drivers during install. It will not even recognize the HDD if I enable AHCI in the BIOS.
I have to wait until after the install is finshed in IDE mode, then, apply the reg hacks and copy iastor.sys to the drivers folder, reboot into BIOS setup and enable AHCI mode for AHCI to load.
I've run out of ideas.

Have had similar problems...

ACHI driver issue W7x64

Am trying to find the time to reinstall, but there are a number of links and ideas already in the thread url above...

If you cannot get Windows 7 to install AHCI during setup do the following:
1) extract and merge the reg file attached
2) reboot and immediately enter the BIOS setup to set your SATA mode to AHCI; save and exit
3) let windows reboot out of the BIOS
4) Windows will install all necessary to use AHCI; you will have to reboot one more time to finish this PNP
5) now upgrade your controller in device manager to the latest Intel IMSM-pointing to the extracted inf
Windows 7 (x64) Ultimate will now update to the Intel drivers and force a last reboot. This works flawlessly, but, XP (64) and Win 7 RC1 and Enterprise (I used this RTM build 7600 to test before October 22) all installed during setup; how can RTW build 7600 not!!!!!!!, no matter what.