Hi,
extending the Java classes to support a new assignment type is somewhat tedious. Extending the WorkOrderAssignmentTypeDelegateFactory cannot be done directly by specifying a custom implementation in the config panel, instead you would have to replace several other classes that are using the Factory class (anyone, please correct me if I am wrong).
If you are bold enough to use AspectJ, you can extend the getAssignmentTypeDelegate(...) methods without replacing the classes that are using the factory. If you want to try this and need advice, let me know.
Regards, Daniel