I do this all of the time. Heck of a lot easier to do than finding a mint gray dash. I use Specialty products.They are made by PPG. I apply the stuff with a small air gun made for detail work. Use a small tip. To do this right you have to remove the dash from the car. First clean the pad with Simple Green,409,soap,etc. I use a toothbrush to get into all of the fake stitching. Use an adhesion promotor. Spray on the new color and let it cure 24 hours. I've always stripped the pad down to nothing before starting. Take off the wire harness,glove box and I drill out the rivets that hold the inner steel reinforcement on. There are two metal pieces. I sandblast and paint those after the pad is painted. No sense in putting rusty parts back in the car. Make sure you paint all five of the major parts at the same time so the color matches. The five parts are the pad,glove box,instument surround,lower steering column cover and the top speaker grille. Make sure you remember to use the adhesion promoter or the color will flake off after a short time. No need to use a primer or sealer on vinyl if you use the promoter.
Edit: They make a special cleaner that removes ArmourAll. Make sure you use it after you clean the pad.