This task can be accomplished by setting comma-separated values for the ListenPort property in the engine.properties file:
Example
ListenPort = 8901,8902
In this case, the engine will listen to incoming connections on ports 8901 and 8902. Note that all clients will be able to connect to any of those ports with the correct login credentials of any acceptor session.
If you need to specify a dedicated port for each acceptor session, you can just give one client one port (say, 8901) to connect and give another client a second port (say, 8902) to connect, etc. Hence each will have an acceptor session working on a dedicated TCP port.
For more details about FIX engine parameters, please follow this link - FIX Engine parameters.