You could use the -pyeval RV command line option to execute your script:
/Applications/RV.app/Contents/MacOS/RV -pyeval "from rv import commands;commands.addSourceVerbose(['syncflash,start=1,end=500,interval=1,fps=24.movieproc']) "
Alternatively you could also have your code executed as part of a python package in RV:
How do I write my first package in RV?
I hope this helps,
Bernie