http://geocities.com/thelightsguy/waterblock_clamp.gif
Well I thought of this when I first read the post. Took me about 2 minutes to do the gif in Fireworks. Well the way I think of it you can use a regular heatsink clip. Then you use a pvc tube and put a spring in it. This goes in the middle of the clip. The you use the screw to tighten the waterblock. If the clip is large enough the screw and the pvc pipe with the spring in it can be as large as the cpu core so the weight of the block is right on top of the core. I don't use water cooling because I don't have the money for it but it's an idea. I hope this can help someone.
John