Content based receiver determination with Seeburger AS2 adapter

We are planning to use the Seeburger AS2 adapter on our XI 3.0 installation to post custom XML documents to XI from external business partners. The problem we have is to do the receiver and interface determination based on the xml message type that is submitted. How can we identify what is the name of the root xml node (which is representing the message type that was submitted to us) during the receiver determination and specify conditions for the receiver determination based on this? We can not use the Seeburger Classifier module here as this is only determining the mapping name to be used for an EDI conversion but can not handle any type of XML message.