I believe this is how you want to wire the switched to work. I am a little tired after a long couple days of tourny play so try it and see how it goes.
The basic idea is you have your normal switch inline with a switch that is set to fire at all times. When you pull the trigger the contact is broke on the switch that is set to fire at all times while the trigger switch intiates the firing sequence. When you release the trigger switch the secondary switch is then reactivated causing the marker to see a second trigger pull.
Running a stock board may create some issues because it may not be quick enough to pick up the second trigger occurance. You might have to switch to a chaos board to get the trigger pulls you are looking for.
Use the image above at your own risk. Like I said before a couple days of tourny play doesnt havent me thinking real straight right now.