Here is a build up demo: http://web.mac.com/mikeharrison/mh_backpac...ions/page1.html
The link doesn't explain how to attach the "completed pump" you are referring to but I will explain how I did mine. Buy four round head wood screws at least about half the size of your baby finger and some washers. You will need to seperate the lower tray and position the pump where you want it. Sitting the pack awkwardly on my knee, I then guesstimated where the pump was from the back and drilled small pin holes with a pin vice through the tray and into the pump. I then screwed the wood screws in from the back using the washers, into the pump. I attached the four screws two in the top, two in the bottom, completing one hole at a time (attaching screw) then pin drilling the next one etc.