If you previously connected to API v1, to connect to the API v2 only 2 modifications are needed, if you already have a working client for the API v1:
In order to access the API v2 you will need to adjust the port number you connect to: "188.8.131.52:7701" using TCP/TLS. The IP address in the example is that of the OT&E environment.
In order to successfully communicate with the API v2 you will need to change 1 section of the header. For API v1 the header mentions "tmch-1.0", to connect to the API v2 this text needs to be changed to "tmch-1.1" By making these small changes you will already be able to connect to the API v2 and make use of the enhancements. Please be aware that if you would like to submit Abused Domain Name Labels via the API v2 further modifications are necessary. For a detailed overview of the API v2 please refer to: TMCH API2 Documentation & XSD