The Promise FastTrak 100 was, if I recall correctly, an ATA controller and not a SCSI controller, although it did support RAID operation. It is a very old controller and I do not recall any drivers being released after the XP version that introduced support for 48 bit disk operations to allow you to break the 132Gb disk barrier (which SP1 or SP2 of XP also introduced support for.)
So are you trying to work with a PCDOS or a WinPE Ghost Boot Disk? Which version of GSS are you using? Is your question about SCSI separate from your question about the Promise controller? If so, which make and model of SCSI controller (or SCSI chipset) are you working with ?
Finally, what size hard disk do you have on your system?