If you had the time could one not just use specially cut metal blocks in place of solder balls? I suppose you might want a grid of ceramic rods or something to hold the blocks in place while soldering with a heat gun but one would think that could work if you had a conductive paste that you could apply&heat to work with.. In theory I suppose.

This gets me wondering, People use rear window defroster paint in place of solder&resistors when overclocking their G4s and portable G3s, What is the resistance like with this stuff? Might it be usable? I have never actually played with it in this manner so I have no idea.