Saffert05

I have a 96 SS s10 and attempting to convert it to a manual and cant fully comprehend how the clutch master cylinder mounts. I have to locate the area n hole saw the fire wall but i guess I'm failing to see how the cylinder will stay locked in? My buddy has a 98 blazer etreme and his firewall has two layers with the square hole in one side of it so he hole sawwed the layer n easy peasey he was done. I'm over here like i don't have that square, do i need to cut a square out or???
Any help or pics are extremely appreciated