CC2530: Defining Custom Cluster, Commands and its callbacks

Part Number:CC2530

Hello,

I need to define custom cluster, its commands, its attributes and callbacks for commands.

So I understood how to define custom attribute and its commands. Also I got a jist of how I can define a callback.

But I am unable to understand how will that custom callback be called once the required custom command is recived, can anyone help me understand  this?