I have recoated every single interior part I have. I have also converted all the interior chrome to black...both metal parts and plastic parts. Note: I use a different method for metal parts; this is what I do for plastic parts and vinyl.
You don't have to use the adhesion promoter, but you do have to have them perfectly clean.
First: wash them thoroughly in warm water with Dawn dish soap. Then rinse them thoroughly and let them dry.
Second: get some 90% isopropyl alcohol (not 70%) and a bunch of white cotton cloth from t-shirts or whatever. Put the alcohol in a spray bottle and spray the part you want to coat. Wipe it with the white cotton cloth. Repeat until nothing comes off onto the cloth. Use q-tips to get into crevices...same thing about repeat until nothing comes off. The alcohol evaporates and leaves NO residue. It also dissolves oil based and water based whatever that is on the part. While you are doing this, make sure you keep washing your hands, too, so you don't get oil from your skin on the parts. Once done, it is ready to coat. If it will be a while before you are going to, put the parts inside new clean plastic bags for storage.
Third: use SEM. In addition to the colors that are already in spray cans, they have color charts and can mix custom colors. Those cans of color aren't in a rattle can, but Preval sprayers are cheap and they produce an ultrafine mist that is even better than spray cans. The Preval is a compressed air canister that screws onto a jar where you put the paint. Lightly spray the parts for your first coat, and then once you have a mist of it on there, put on a solid thin coat. Then another. One more if you really think it is necessary. Top coat clear if you want, also. Let it dry (which is fast), and then wait a couple days before you wax it. Easy, and it won't come off. It will rub off with serious abrasion like the original coating, but you would really have to try. Normal wear is not a problem.
I've done this lots, including the steering wheel. So long as the piece is perfectly clean, it will bond perfect. So long as you don't spray it on too thick, it will look beautiful.