1. Watch this video and notice how to insert the locking pin. Ignore the rest of the video.
http://www.youtube.com/watch?v=2fFx8SPiTSc
2. Put the crankshaft in the locking position. In order to do that quickly and with minimum effort:
a) remove the undertray
b) put the car in the fifth gear
c) handbrake and two stones on a front wheel, raise the other front wheel on jack;
secure the car with something more stable, a jack stand or a log
d) turn the free front wheel s l o w l y until the crankshaft is in locking position; you'll need assistance/help and if your car is an auto you have a problem
2. Insert the locking pin or a metric 6 bolt
3. Remove the bolts from the INTAKE camshafts ONLY
4. Replace the belts
5. Remove the locking pin, start the engine and see what happens
Tips:
You'll need some tools and some improvisation for (4), but it can be done without the special "legal" tool kit.
A mirror placed at an angle of 45 degrees in the proper place and a torch will tell if the crankshaft is in proper position before inserting the pin.