Don't know if this will do the trick but I use a small program called "Loop Midi" along side "Reaper" and it works for me.
Not sure if you are wanting to use sound to trigger but it might work there too???
I waqtched a vid by Christian Jackson on youtube on how to set up.
very good vid...

search youtube for "Christian Jackson - How to set up Reaper for time code"

good luck and let me know how you go.

regards