Here's a decent step-by-step for it...
1. Sand the dash with some 80 grit wet and dry, to roughen up the surface.
2. Clean off and allow to dry.
3. Remove all fluff with a tack cloth and apply 3 -5 coats of Plastic Filler-Primer (available from Halfrauds), allowing to dry fully between each coat, 24 hours if need be.
4. Sand smooth, using wet & dry paper. Use a 80 grit wet, moving upto 1000 grit.
5. Clean off and allow to dry.
6. Remove all fluff with a tack cloth and apply one coat of plastic primer, and allow to dry fully.
7. Sand until super smooth using wet 1000 grit wet & dry.
8. Clean off and allow to dry.
9. Remove all fluff with a tack cloth and apply one coat of colour, and allow to dry fully.
10. Sand with lots and lots of water, using an even finer wet & dry paper. If you do not have any super fine paper, take two sheets of 1000 grit and rub them together. If at any point in this sanding process, the paint looks scuffed - apply another coat of paint otherwise this will show up after laquering.
11. Clean off and allow to dry.
12. Remove all fluff with a tack cloth and apply 2 - 3 coats of laquer, and allow to dry.
13. Polish, polish and polish like there's no polishin left it you!