1st. Remove the screws under the dash gauge area, you'll have to lower your steering wheel all the way down. Then after that you can remove teh screws from the underside. You then should be able to just pull it out...GENTLY...
2nd. Remove the 3 screws holding in the guage cluster, I belive there is one on top and one to each side of the cluster.
3rd. Don't quite pull out the whole clustor yet, becuase it has a wire harness on the back of it. Pull that out gently and then unplug that, make sure you don't rip any wires out. There also on my car was a little zip tie thing I had to cut. After that just remove the whole thing out.
Warning!! After this step I haven't actually done, just watch people do and reading..
4th. The plastic part should snap off, but be careful not to hit anything or break anything.
5th. There is a couple of screws in which the black part of the cluster is held in by, remove these before removing the black part.
6th. Now get your indiglo guages prepped and set. Since you have already installed some of these you know how to slide them in and not hit the needles so that they will uncalibrate. Double sided tape or glue...whichever you choose to use.
7th. Get the wires and wire it up according to the dimmer, power, and so on. You should already know this part. Red/Black wire is the 12V for parkign lights and dimmer. Black is duh ground.

Reverse steps then you're good to go.
Oh yeah may sound like a common sense thing, but test it all out before you put it all back together.
Good luck,
Jason