how did they over paint the letters?

Most of those are from the factory or a graphics kit. If you know a painter then make(or have made) a stencil of what you want then have the color you want sprayed on and clear coated (a extra clear coat on the hole frame and wheels wouldnt be a bad idea). Or if you know a graphics company have them print you off some and stick it on, but again a clear coat over them would ensure they stay on there

I'm thinking about taking a shot at this. I plan on using acrylic paint covered with shelter tape or a clear coat.

Go with the clear coat it will be heavier butdont worry at some point or another you will be glad its only the clear coat that came off and the the graphics