Well, thank you very much @BrettZimmerman - That did get me into the panel to edit, but no cigar either. It appears to be only the open invoice header table fields that are available. You are unable to add any other tables.
I did find this link regarding adding a link in an ALE lookup but it doesn't seem to fly with a panel modification. But maybe I am staring at it the wrong way.
https://90minds-com.socialcast.com/messages/22736610?ref=stream