[VRM]

Paul,
I've got a real steady hand when it comes to painting, but even in 1:24 hand painting a pinstripe is beyond my skills. I paint with a sable brush (10/0 size I think) like what Jamo mentioned, but I also strip out all but about 10 hairs.
I would just make a set of decals - do you have access to a colour laser or ALPS printer?
Put a bit of tape on the body and then draw the line with a pen, then remove and scan the line you drew. Then trace it using some drawing software and print in whatever colour you need.

I use Illustrator/CS. It is a high end professional program, but you can use a number of others including some that are pre-loaded on most PCs.

Steve