The Elk Security Module add-on for the ISY allows control of the ISY from the Elk, or the Elk from the ISY. I have my Elk M1G configured to tell the ISY to open/close Z-Wave locks.
You can find more information here: https://wiki.universal-devices.com/index.php?title=ISY-994i_Series_INSTEON:ELK_Security_Module.