Excuse my fucking ugly texture pack.
Explanation:
The pressure pad is attached to an RS NOR latch, which acts as input 1 to the XOR. The output is attached to an RS NOR which acts as input 2. It also outputs to the clock.
When the pressure pad is activated the inputs become unequal and the output becomes 1. This activates the RS NOR, which causes the inputs to be equal again, deactivating the output. The output time can be extended by placing repeaters between he XOR output and the 2nd input.
Oh, there's also a reset button. That's what the wiring on the right does.
You'll need to use a different kind of clock if you want it to reset automatically. Mine was just to demonstrate. I'm sure you can figure that out yourself.