After upholstering my door panels and sun visors, I decided to try my armrest. I found that you can remove the rubber covering, so that if your material were to rip or you got tired of it, you can revert back to the original with no problems.
So, first you need to remove the latch, and all of the other screws. Be sure to use a tiny phillips head, you round the "teeth" off of the inside of the screw head, and you're pretty much "screwed".

The bottom with the lid piece removed. This was a black armrest, so I'm not sure why the plastic is brown. Oh well.

Remove the top rubber piece.

Break out your weapon.

Spray moderately. Too much, and your fabric will turn white, and be hard in that area. Too little, and when you put your arm on it, it's going to release.

The finish.

Installed:

Material used:

You can get it at walmart. $3.00 and something a yard. I bought 4 yards, and came out a little over $13.00. You can also buy vinyl in your color of choosing for $7.00 and something a yard.
The armrest has foam on it already under the rubber piece, but if you want it super soft, just glue more foam to it. Piece of cake.