Yes there is.
Edit the Netrender.cmd file in your A:M program folder...
REM starts the rendermessnger in two instances for a dual core machine
REM renderserver should be started first
start renderserver_64.exe
timeout /t 15
start rendermessenger_64.exe
timeout /t 15
start rendermessenger_64.exe
duplicate this portion for as many nodes as you need to start...
timeout /t 15
start rendermessenger_64.exe
That file will get reverted it you later do a Help>Reset All Settings so you may wish to save a copy elsewhere.
OpenMP enables multi processing, which probably has no advantage for NetRender.