There isn't one, but you can replace the tap stompswitch with a jack for external control. Be aware that the tap stompswitch also controls the preset system, so you'll be messing with that too. You'll need an isolated mono jack like this. Here's the steps to do the mod: 

1. Unsolder the wires from the two terminals on the tap stompswitch.

2. Use a wrench to remove the tap stompswitch.

3. Use a wrench to fasten the isolated mono jack to the enclosure in place of where the tap stompswitch was.

4. Solder the two wires to the mono jack.

On older versions of our pedals, we used latching stompswitches, which look like this (the one in your pedal might only have two terminals):

On new versions of our pedals, we use momentary-close switches, which look like this:

So the signal that you send to the pedal has to be the same as whatever stompswitch you're replacing.