For the WLAN via CLI enter:
use association-acl-policy CLIENT-BLACKLIST
You must create the Association ACL...ex:
!
association-acl-policy CLIENT-BLACKLIST
deny AA-BB-CC-DD-EE-FF AA-BB-CC-DD-EE-FF precedence 1
PERMIT t 00-00-00-00-00-00 FF-FF-FF-FF-FF-FF precedence 1000
!