Yes, you can set the tempo via midi with the Tremolo2! To send midi information to the Tremolo2 you'll need a Midibox (http://www.empresseffects.com/midibox.html). This will take midi in and let you send it out via 1/4" jack which you'll plug in to the Tremolo's control port.
Then you'll just need to go into the Tremolo2's advanced config and set it to listen for midi. Then, you can set the Tremolo2's tempo via control change messages.