You should sand it down with some 400 grit sandpaper and then use a tack cloth to pick up every little debris. Don't know if you need to primer but you could probably paint it straight after sanding. I think that SEM's paint is best in terms of painting the interior.

On another note, have you considered just rewrapping the entire dash in white? Much better and you won't have to worry about the paint fading over time.