I'm assuming you are disassembling the psp and removing the trim.
1. clean off the trim with water to remove oil and anything else
2. Sand the trim with sandpaper, do your best but remember you are just trying to provide a "grip" for the paint
3. clean off the trim again
4. paint the trim with any paint made for plastic. I recommend krylon paint.
5. Spray as many coats as you want. follow the directions on the can
6. Let it dry for a while following the directions on the can
7. Spray clear coat. You should do a good 3-4 coats to make sure you have enough.
8. LET IT DRY!!! Wait a WHOLE day or two before putting it on again otherwise it will smudged and sticky
9. done