The physical swap is easy...the problem you'll run into is the difference in the connector. It's not that hard to shove something like a toothpick into the connector and pull the wires out and move them to the new connector. I believe you can also pull the gauges apart and disconnect the 'harness' from the inside and do the swap there. I haven't verified this though!
I know this is an old post, but do you have the specifics on how to do this swap? I'm swapping my original 03 gauge cluster for an 04 cluster and am running into the problem of the different connectors.