To configure multiple Basic Service Set Identifiers (BSSIDs) on the Access Point (AP), refer to the Configuring Multiple Basic SSIDs section of Configuring Multiple SSIDs.
Access points /Brdiges must contain G Radio / A Radio to support multiple BSSID. The B radios do not support multiple BSSIDs.
You need to have IOS 12.3(4)JA or later in order to be able to configure BSSIDs. For detailed information refer to Cisco IOS Software Deployment Release 12.3(4)JA
Configure / Configuration issues