Are iDocs are required for publisher channel, or is there another way to get event notification. It looks like the SAP User driver requires an iDoc through TRFC to provide the "event notification" on the publisher channel.
The SAP User driver does require the USERCLONE IDoc generated by CUA for Publisher notification since that is the standard mechanism. However, since the driver does not utilize most of the data in the IDoc, if they have some way of creating the 'trigger' IDocs that the driver uses to be notified that it should read the data from SAP it would work.
The trigger IDocs look like this: