Physical Track call button

I have a 2 part question. Where do I connect a physical track call button to the phidget interface? So that I can use it instead of the keyboard. I have read every topic that I thought might talk about installing a physical track call button, and have not seen any.
Now if this is doable. The latest PCLP beta version 5.19 offers the ability to use the yellow flag with a button connected to the phidget. So it stands to reason that I should be able to install a adjustable voltage regulator at a point, so when I trigger a yellow flag the voltage is reduced. With out having to buy a third parties device that offers the yellow flag option. What do you think GUY?????

Look at the manual your phidget interface , in the manual there is a description of how to connect a external button to the phidget interface.
In Pc Lap Counter just go in the phidget setup screen and in the "track call" tab page specify the input IO to the command you want the button to generate (http://www.pclapcounter.be/phidget_interface.html)

Edit: about yellow flag and voltage reduce, Pc Lap Counter can activate a digital IO of the phidget interface but i assume you will have to connect a device to the phidget interface which will reduce the power but as my knowledge in electronics is very basic i can't tell you what you need exactly