I think I may have used AutoIt in one of its earlier incarnations (or something similar) but I'm not that familiar with scripting tools these days.
I'd start with trying to emulate the stop/start behaviour but accept you'll need to know if a recording is in progress (it's a beginning at least for test purposes).
Most scripting languages should allow using a 'shell' or executing a command-line statement.
and an associated 'net start' command from the command prompt is what you need. I've had a quick look at AutoIt and it should be able to do this easily.
net stop "NPVR Recording Service"
As for monitoring recording status, I'm not sure if it's available externally to NextPVR and is probably only available to plugins within the NextPVR framework. I may be wrong though but that's generally how things were with gbpvr.
You could make an assumption by querying npvr.db3 but that gets more complex and I'm not sure if that's within the scope of AutoIt.