What about getting one of those new fangled Laser line things? They make adhesive pads to stick them to different objects. Just a thought.
The only there way that I have seen it done is by eye. Start the stripe where you want it and then pull 2, 3, 4 feet out and lightly position it, go 2,3, 4 feet more and do the same. Make sure that you have some tention on the tape so when it is right and the press it down it dosen't bunch up in the middle or end. Good luck.
