I use Dupli-Color DE1634 engine enamel. It's similar to the OEM Honda paint, a bit less glossy and black-black, very durable. I would NOT recommend DE1635 - it looks a little closer to the original, but doesn't stick to either D-C primer or bare metal well at all.
I assemble the cases with all screws medium-tight first, then pull the screws out and use two old ones to hold it together while painting, with old side covers to prevent overspray (I've got a bunch lying around, and I'm too lazy to mask). Everything else I paint separately before assembly. I like the look of black screws, just not painted black.
I also heat the paint and work beforehand with a small space heater, I like it when both are around 90F or so.Ray