soldering onto the L bridges

How hard would it be to solder 14 wires onto various L bridges on a palimino?

I am very confident with my soldering skills, as I have repaired several laptop motherboards, and cellular phones.

What wattage would be sufficient? What ratio of lead and tin would be best suited for this purpose, or should i just spring for silver solder?

Soldering onto an organic substrate is highly risky IMO. Plus aside from the technical difficulties how are you going to get the wiring out from under the heatsink? I assume that you plan to unlock multis and mod for upper/lower ones so changing the multiplier set would need wires coming out from under the heatsink where there is like 0.8mm clearance.

If you are that nuts and are looking for a new processor soon, then use a low-wattage iron with an extremely fine needle bit. I would also use a very low melting point solder as you will have to heat up the substrate quite a bit to warm the dot in it sufficiently.

It's REALLY small on those bridges. It would be REALLY hard to solder. Seriously.