I'm not sure why you would want to do this? Basically, you are just pleading guilty. From what you said, there is no way the cop was able to pace you properly to get an accurate reading of your speed. Why not just go to court and challenge the accuracy of the pace? I have challenged cops in court several times and won. It really isn't that hard. Honestly, I think these guys get complacent because they are challenged so rarely. I say, do some research, make a diagram, show where you were accellerating and slowing and where he was. I bet you will do better than you think.
Jimbo