I know your looking online but our local mall does a great job of ball cap embroidering. They can take any PDF file you give them and put it anywhere on a cap. Not bad prices either - I think between 5 & 8 a cap depending on choices...
I second the recommendation to go with a local walk-in style store. In this area, there are literally dozens of companies that will do custom embroidery (look in the yellow pages!), and you have a better chance of getting what you want if you can show them exactly what you want.