So, you have a flash drive with the iaAHCIC.inf and associated files on it, but pointing the load drivers to that file does not load a driver? These files do come from the f6flpy-64.zip file for a 64 bit version. I think that file loads the AHCI and RAID versions, but you might also try the iaStorAC.inf file.
When you point the installer to these files, it should recognize and load them....Then you should be able to access the RAID array.
Have you looked at the RAID OpRom during boot? I don't remember what key combination it takes, but I am assuming it is still intack.