I really love how this mod sounds and I am at work building the LFO now.  As per the schematic you posted. But I am confused to how you accomplish this:

"The trigger pulses can be used to regularly trigger the “ONâ€ or “holdâ€ functions of the Speak&amp;Spell."

I really want to incorporate these features but after looking at the schematic of the circuit and the large diagram I am still not sure about it.  I am assuming it has to do with the switches in the cloud and D1/D2 and E1/E2???  

I was also curious about the power switch?

Thank you very much for your time.