Backup Exec modify SelectionList with BEMCLI or any other scriptable utility?

I need to write a script using PowerShell + BEMCLI and/or any combination of utilities available on a Windows Server to modify the SelectionList of an existing Backup Exec 15 job.

This does not appear possible with the commands available in BEMCLI.  Is there a workaround?  I'm open to any suggestions, including modifying underlying BE SQL tables directly.

The client being backed up is a Linux-based NAS that does not support a BE Agent.

Thanks,

-fg