Switching two MacBook motherboards
You can check out the directions on iFixit here.
There are a lot of steps, but none of it is really rocket science. They explain it in detail.

My bigger question would be whether the two boards are compatible.
Based on the specs for each one (2,1 / 3,1), the main differences are (respectively):


Processor: TS7400 / TS7500
Video Card (integrated): Intel GMA 950 / IntelGMA X3100
VRAM: 64MB / 144MB


I'm not sure how these effect logic board compatibility, but I'd be careful.

Also worth noting that the white 3,1 actually supports 6GB of memory (unofficially). Get it here.

Hope this helps.