@WickedBro You're half way done. The ISOs you got are for retail channel, so things are more easier. Like XP, prepare the ISO by replace generic OEMBIOS set with matching OEMBIOS set - you need to compress them/use compressed set. set the channel in SETUPP.INI (like in XP). optionally set the OEM:SLP key in answer file or manually put in while installing.
Thanks a lot! The channel was the problem (i've just changed zeros to OEM). Now do i need to make WINNT.sif for the cdkey to be auto inserted, or i can just edit PID.ini ? Thanks again Tito.