You can purchase the Rustoleum tub and tile kit.
Here's a different kit that may work for you: https://www.youtube.com/watch?v=9qkssyahu0U
Be sure to do the recommended prep to a t. It will help it last longer. They tend to peel in a few years but will do it sooner if prep isn't followed.
Be certain you want to paint, even using a kit. You will have to replace the enclosure within a couple of years.