so, if you are like me, you have setup a VLAN for your wireless traffic and have setup a Layer 3 outbound rule on the Router. you may be able to add a rule that allows traffic to the IP of the printer. another suggestion would be that you allow that user access to the LAN by setting up a different SSID. i have a mix of users and i do allow certain Administrative types to use my WLAN on the Corp side vs the Guest side.
-shane