I did mine by first thoroughly cleaning & de-greasing the area to be painted and insuring that any loose paint is removed. Then fine-sanded any remaining old paint edges to a smooth feathered edge. OR - use paint remover to remove all of the old paint. Use Scotch-Brite or fine sand paper to rough up the bare metal or old paint surface for better adhesion of the new paint. Be careful NOT to rough up or scratch any of the surrounding decorative bright metal surfaces.
Next, I very carefully masked off the areas to be painted using that blue masking tape that paint stores, etc. sell. I used an Exact-O knife to trim the masking to a "perfect" edge then sprayed the color on. The tape should be slowly pulled off as the paint begins to dry or else you will pull up the edges of the painted area too.
The tricky part was to apply a heavy enough coat of paint so I'd only need one coat and so it would "puddle" smoothly and hide the underlying texture of the base surface - all without over-flowing the taped edges. The instrument panel must be laying perfectly level so the paint doesn't run to one edge.
Of course if you have a good steady hand and an artful technique, you can forego the masking tape and use a nice soft, medium-length artist's brush to lay the "puddle" of paint in by hand and work it carefully out to the edge of the depressed area. The paint must be thinned out (almost "watery") so that it flows easily. The paint should be laid on thick enough that it will "flow" into a smooth surface before it dries or you'll see brush marks when it dries.
I used a lint-free rag with some paint thinner on it to carefully wipe away any paint that got beyond the edge of the depressed area after the tape was removed.
Post photos of your completed job if you can!
Earle