UnRAID is based on Slackware so the way to do this would be to create a Slackware VM and then follow the instructions to create a statically linked version of the agent from the sources that would result in a binary that can run on Unraid. There are also some users that need to be created and these should probably be redone on each boot. Thinking about it this could be done using the User Scripts plugin with a simple script set to run on first array start rather than writing a separate plugin.
I already have a Slackware VM for other reasons, so if I can find some time I might have a go at doing this myself.