Import your poly WAV file into your Multitrack project in Audition (File > Import...). It should appear as the following when dragged into a new track, which includes all of your inputs on one track:

Go to the Files Window on the right hand side and locate the file. Click on the arrow beside the name of the file.

You should see a list of Mono tracks that will correspond with the input on the Rodecaster.

Drag one of the tracks to your project:

Dragged the needed inputs into your project and you're ready to edit!