Brain Jr for Yamaha KP65 conversion to MIDI?

I'm new here, and hoping this will

I'm trying to figure out a way to convert a Yamaha KP65 kick pedal switch to midi to enable velocity. The unit is built to convert velocity through a drum module. I'm looking to use it to trigger midi through Ableton Live. In order to do this I need to convert the output of the KP65 to MIDI. It occurred to me that I might be able to do these using the Livid Brain Jr.

Now, I may be looking at this too simplistically, but my thought is that the voltage output of the sensor on the KP65 can be captured through an analog input on the Brain Jr, and converted as if it were a velocity sensitive resistor. In principle this makes sense to me until I look at the connector of the KP65 - it's using a TRS cable.

So, my question is, can anyone point me to how I would go about measuring the output of the KP65, and then understanding how to wire it to an analog header in the brain Jr? 

Once I have this down, I can create a Max4Live device to handle the MIDI Messages.

Thanks!

Robin.