Each M3 in a chassis is logically separate from a management and a networking perspective. You will need to network each into the environment as if they were separate units and manage the "local" config (VLAN info, IP info, Net Management Info, phyical ports, etc) separately. If you like, you can set these up as master/local where one is master and the other 3 are local so that the "global" config (all AP-Group related config, policies, aaa, etc) and monitoring is managed from one spot. You can pick which one you want to be the master, really doesn't matter. This would be the same if they were separate controllers. Please be sure to follow master/local design guidelines in the VRDs however.