Well, in our Beat707 project, I searched on how to send MIDI Clock Sync, which is 24 PPQ. So, at every 24 PPQ I send a clock signal via MIDI.
MSerial.write(0xF8); // Midi Clock Sync Tick
You can also send Start/Stop to Live's Transport:
MSerial.write(0xFA); // MIDI Start
MSerial.write(0xFC); // MIDI Stop
Hope that helps, otherwise, tell us more on what you need exactly.
Wk