Personally, I think you should stencil it on with paint. Basically, go to an art store and buy a role of "Frisk Film". This is basically a giant roll of low-tack, clear contact paper. Then you create your stencil, cut it out with an X-acto knife, apply, spray, remove, voila!

I have done this with great success in the past. But, you have to take your time. This method does create a lot of room for error, also. I wish I had some photos of my old cars from college that I had painted up...

Bart