I intially set about tearing apart my dash to locate the DIC pigtail, but decided since I was that far into it I'd change my dash bulbs. It's not a hard procedure, but here's how to do it anyway.
(sorry no pics, I couldn't find any batteries)
First off, grab a 7 mm socket, some extensions, a u-joint, some small torx bits, and a screwdriver.
First, block your wheels off and put the car into "1." This will make it easier to remove the console.
Now pull the staple out of the shift knob and pull the knob up and off. The whole console will now be able to lift up and towards the back of the car, clearing the shift lever. There are no screws holding it down, but you will have to reach underneath an disconnect the ashtray and gear indicator lights.
With the console out of the way, it's now easier to get at the two 7 mm screws that are under the radio bezel and far towards the firewall. These are the hardest screws to get at of all of them. You'll need your u-joint and some extensions. Take 'em out, and the radio bezel will pop right off.
To the left of the radio there is a silver 7 mm screw you'll have to remove before you can pop off the gauge bezel. One it's gone, the whole thing pulls right off. Keep an eye on the top part to keep the tabs from snagging the dash pad. The central vents will probably fall off at this point, as the bezel holds them in. You'll have to tilt the steering wheel all the way down to pull the bezel out, too.
Now there will be about a half-dozen silver screws surrounding the instrument panel. Figure out which torx bit it takes and start removing them. The clear plastic cover will come off first. If the black plastic piece surrounding the panel doesn't come out as well, you must've forgotten about the two screws at the bottom of the panel recessed underneath it. They're the same size. Take those out, too.
The panel should be loose now. Tilt the top forward and lift the bottom up to clear two small tabs that hold the bottom in place. Now, don't try pulling it clear out because you haven't unplugged the pigtail yet. Tilt the right side towards you and look behind the lower corner to see it. The side of the pigtail closest to you is blue, and the back is grey, but don't try squeezing the tabs on them and pulling on them, because they don't come out. Just pull on the whole thing and it'll unplug from a little black piece (this sounds kind of confusing, but just trust me and pull). Maneuver the panel out.
Flip it over and there should be a black panel covering the back. You'll be able to see the backs of the bulbs but you can't pull them out yet. There are another half-dozen little silver screws holding this cover on (same size as the ones that held the panel in the car). Take those out. There are two more black ones on either side of the pigtail connector, but nevermind those.
With the black panel off, you'll see the circuit board with all the lights on it. There are five large bulbs that light up the gauges themselves (the rest are smaller and light the warning lights, those shouldn't be burned out since they're not used as much). Grab the flat grey parts and twist them counter-clockwise a half-turn and pull them out.
Before you did all this, you should have gone to your parts store and ordered five PC 194 light bulbs (ran me $4.70 at AutoValue). "But Anthony, only one of the bulbs actually burned out! Why do I need five?" Because you might as well change them all while you're at it! Anyhow, pop the five old ones out and twist the new ones in. The new ones might be harder to twist, so don't be afraid to use pliers to get them in there.
Read all of this backwards to figure out how to put your car back together.
As for inter-model compatability, it's anyone's best guess as to if these instructions will work for you Cutlass, Lumina, Monte Carlo, or Regal. But they sure as hell work for a Grand Prix.