Okay, do you want to say, "anything that begins with this mac address I want it to have Y role", or "I want to put in a list of mac addresses and only these macs will be able to pass"? Which one?
For the first, you would create a user derivation rule, instead and attach it to the AAA profile of your WLAN (Configuration> Security> Authentication> User Rules Tab..
For the second way, you would enter a list of mac addresses in the local database, configure a mac authentication profile and mac authentication server group and assign it to a AAA profile (user guide Chapter 19: MAC Based Authentication).