Ok, here goes.
You need:
- Thin wire. People here will advocate 30AWG, and certainly there are points where this would make it easier, but honestly anything 26 and smaller works for me.
- A soldering iron with a VERY fine tip. The one I use is a Radio Shack "soldering station" special, with a replacement nib that's ultra-fine. It's switchable from 10W all the way to 40W. You don't want one that's TOO hot or TOO cool, I usually leave mine set at 20W and that does the trick.
- Desoldering braid. TRUST me you need this.
- Flux. This isn't strictly speaking a necessity, but it might help for the tough-to-make-it-stick points.
- Exacto knife. Sony coats their newer boards (v4 and up) with a plastic coating. I beat my head against one install for about 2 hours when the GT3 kit first came out... then lo and behold someone who solders for a living (a friend of mine) has a look at it and says "oh yeah polymer coat!" D'oh!
- Wire strippers. Although, I suppose the Exacto knife would do for this in a pinch.
- Glue gun. TRUST me here. You want a glue gun. Once a tricky point is attached, you hit it with a blob of glue, and BAM! No worrying about whether it'll come off when you nudge the unit.
- Electrical tape. 'Nuff said.
- Quality screwdrivers.
- Razor Blades (to make soldering to legs of chips easier).
- Double-sided foam sticky tape...
- Continuity Tester/Multimeter.
Well, that's what I use. I think that's everything... *shrug* if I think of something else I'll post again.
Oh, yes - PATIENCE and a steady hand.

Some days I just can't do modding, if my hand isn't steady I just wait until later. No point trying when you're shaky.
... Gurm