There may be an easier way to do this, but if you want the AP to authenticate (using DOT1X first) and then open up the port to other clients that do not have DOT1X authentication as an option, in the past I've used UPM scripting to do something like this. When the AP is authenticated, the authentication UPM script for that AP enables MAC authentication on the port when the AP authenticates and there are masks configured for MACs in the NETLOGIN config and a general set of MAC entries in the RADIUS users DB to authenticate any MAC. The UPM script which would run when the AP is unauthenticated would disable MAC authentication on the port, but preserve DOT1X.
I could write up a configuration for a lab if you have one, otherwise I would have to build a lab to test this scenario and it could take some time.