Another alternative to buttons and screen taps and Pitside Remote S/F setting would be to use an AIM Beacon to set the Start/Finish. You could hook up an AIM IR Receiver into an IOIO Digital IN. Cheap IR receiver alternatives also exist like the Panasonic PNA4602 IR Detector and Sharp GP1UX311QS (usually available at Radio Shack).
The AIM transmitter uses a proprietary transmit pattern to identify it's unique beacon that would probably have to be decoded in WifiLapper. Here is a link to the reverse engineering of it:http://ucexperiment.wordpress.com/2012/ ... ansmitter/
Many people still setup beacons at the track for data acquisition systems like AIM MyChron systems. They are already there, so it'd be cool to be able to use them. The beacon is arguably a more accurate placement of S/F over GPS. And it would automatically set the S/F when it sees it, one less thing for the driver to worry about.
Here's the AIM transmit sequence just in case that site goes down: