Leif, you must drill a small hole in the housing that surrounds the ignition
lock cylinder.  I just looked in the Vanagon Bentley and there is no picture
of this (that I could find).   However there is a picture of it in my
Scirocco/Cabriolet Bentley (a superior book in many aspects) and since the
ignition housings are the same you should be able to use this picture to
properly drill the hole (I have done this several times).  Then you just use
a nail to depress the cylinder retaining spring and pull the old cylinder
out.  You could probably look at where the spring is on your new cylinder to
give you an idea as to where to drill.  If you need the picture let me know
and I'll p-mail it to you (if anyone else needs it too, just drop me a line).
Ken Wilford
Van-Again
John 3:16