Looking at the documentation for the container, you’d need to add the environment variables AUTOMATED_CONVERSION_PRESET and AUTOMATED_CONVERSION_FORMAT with the appropriate values.
As the rockon config does not expose this option, you’d probably need to make a copy of the rockon from the rockon registry and modify it to include the enviroment things you need to set up for your use.
In that template file, you need to change the rock-on name, maybe the container name and add the new environment prompts to change it.
I have a changed definition file as an example. It will only add these values to the registry version. It would need to go in the
/opt/rockstor/rockons-metastore folder on your rockstor server. Then refresh your rockons and pick HandBrake-Custom rather than HandBrake.
You will need to type the profile you want exactly in the prompt when installing the Rock-on, so you may want to copy/paste it to an editor from the standard one.