prepare them like any other part......clean/degrease , prime and then paint with the paint of your choice
I own a coatings business and use a product that is designed to be chemical resistant and to adhere to polymers. The product is called Duracoat. It is very strong and easy to apply. My secret is that Duracoat is just a relabled version of a product made by Sherwin Williams called Polane. I coat gun stocks and bow limbs with it. The limb coating has to be thin and flexible. Once it fully cures, then gas or oil will not remove it. It can be applied over prepped metal or epoxy primer. I use Polane T because at 10-12PSI, you can apply it with some texture. It has a hardener that effects gloss levels. Less hardener means less gloss. The color that I use is called Graphite black. Trust me, its probably the best spray on coating for anything that needs to be flexible.
Black gloss with a brush, sprinkle graphite chips on wear area, to and bottom, let dry & spray with gloss black of your choice.