I originaly had the Per. Gauge pack install but decided to go with the Defi Cluster setup mainly for the JDM look and function but also cause they matched the stock G cluster on the 04 STI so well + monitor the vitials when haveing her tuned.
But to answer your question is to remove the two screws on the cup holder and pull it out, then the rest of center console and vents just pop out with a lil tug. now you have ease of access to the bottom clips of the gauge cluster w/ out diging up the dash w/ a screw driver! Push them in in the front and then work your way to the back and it easily pops out. Now remove the cluster and unscrew the bracket bolts that hols the gauges one buy one. Now this I have not done but would imagine that it would be possible! By observing the gauges after removal, I'd imagine that you can remove the face and then access the bulbs. The removal time for all is 10-20 min tops, so its not hard if you have time to experiment.