I actually just did this, this past weekend. I used the old bars and measured how far in from the ends the holes should go. Cant remember the measurement, but can check.
You have to mount your bars first and rough mount the controls, sit on the bike with hands in position, to work out where your control will be and at what angle. Then you can mark the holes. I put the exit hole in the same position as the originals, on the underside of the bar right in the middle, between the bar clamps.
Pulling the wires was a pain, one side went quick the other side must have had more welding slag inside and took a real lot of pulling and pushing. Lube is the key, plenty of it. If your really giving it some welly while pulling, back off pull the wires back and start again. its easy to catch the plastic wire wrap and rip it all. All and all it was pretty simple. measuring and drilling the holes was the longest part for me.
Good luck