All parameter passing is done in BRITE via a configuration file. As such, creating your own model first requires modifying the configuration file parser (located at Main/ParseConfFile.java) to handle the parameters of your model. You do not need to write your own parsing routines. The Parse method of the configuration file parser stores all parsed attribute-value pairs of a model in a Hash-table, params. All you need to do is interpret the keys and values in this Hash-table according to the semantics of your model, create your model and return it to the caller. For instance, the RouterWaxman interprets the Hash-table parameters as shown in code excerpt 8.
The Model object is then returned to the main caller (usually the main entry point to BRITE, Main/Main.java), which in turn creates a Topology instance with this newly created model. See code excerpt 9 extracted from Main/Main.java.