Configure the AP 350 with a vlan for the SNA machines. You need to associate this vlan with an SSID later. And on the vlan setup webpage you can configure the priority of this particular vlan. Acceptable values are
1. default
2. Background
3. Spare
4. Excellent effort
5. Controlled load
6. Interactive video
7. Interactive voice
8. Network control
Once you choose a type of priority, you can go to protocol filters page, and selecto Quality of Service, For the priority class you chose, set the CWmax and CWmin values. Wireless uses congestion avoidance, so these factors actually determines the approximate random time, for which it waits, before sending data. For voice and delay sensitive traffic such as SNA, you should set the CWmin to a lower value, inorder to account for delay.
http://www.cisco.com/univercd/cc/td/doc/product/wireless/airo_350/350brdgs/brscg/br350c3b.htm#1036478
Check this link for some qos mechanisms that can be applied.
Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus