Hello, old thread, but it could be useful for someone.
Tools: Drill, screwdriver, blank plastic from PC front, wire, tape, switch, PC fan, knife.
Time: ~30 min.
Full step by step instructions with pictures and videos you can find on my blog:http://digitalloupe.blogspot.com/2011/10/pc-fan-system-mod.html
1. Get the tools.
2. Cut the wire of PC Fan (you need to cut only one wire, no meter what color it is (because it is not a bomb). I cut red wire, since my extra cable is red).
3. Clean the ends of the wires of PC Fan and wires of the extra cable.
4. Tie the wires of PC Fan and extra cable (if you have soldering iron, then do it that way).
5. Use the tape to wrap the node and then cut the extra cable in the middle.
6. Clean the ends of the extra cable.
7. Integrate switch in blank plasctic of PC Front. I drilled small holes then with knife cutted out hole for switch. You can do this any other way.
8. Tie the ends of extra cable with switch.
9. Use the tape to wrap the node.
10. Put PC fan in place. Put blank plastic with switch in place.
11.Now you have button to turn on/off your PC Fan.
Remember - it's all on your own risk! Don't touch cleaned wires when they are connected to the power line!