The biggest difference is prep. Make sure you clean the area you're painting really well.
When I painted my cover, it was with a rustoleum can, I think. It was just some random paint that was in my garage. I did a pretty half assed job at prepping. It lasted for two years until I smacked it on a rock and it chipped the paint. I'll be re-doing it when I'm bored.
I wouldn't worry about it too much, you're putting the cover on to protect it from rocks. If you hit a rock it will chip.