I think I've got it but I don't have a way to test it. Basically it's just a "for" that goes from 0 to gamepad.count. You can set which button is being pressed inside of it.
I have no idea if the pin at the Start of Layout is working also.
https://dl.dropboxusercontent.com/u/2383513/linkedOUT/tanks.capx
edit: Whoops, I forgot to set the angles to gamepad(loopindex,0).
And I forgot to mention, whenever using a for you can use "loopindex" to use it on expressions.
Hey man, thanks! I can confirm that it works with up to 3 controllers by adding a 3rd tank. Great job!