Yes that is possible. You'd have to add the file upload field after the wizard finished and update the insert server behavior on the registration page, but there is no reason why it couldn't be done.
You would need to own either Universal Email or Form Builder to have the webassist Digital File Management server behaviors that allow you to easily manage file uploads. The steps would be:
1) add a text field to the database to store the uploaded file name
2) add a file upload field to the registration page
3) apply the digital file upload server behavior from webassist
4) update the insert record server behavior to store the server file name of the uploaded file in the newly created database column