lan,
It's not in Barry's 12 page Addendum
Look at the following on page 3 of the addendum:
Wiring for TMCC Engine Control (Only)
The following wiring methods allow control of TMCC engines, and Legacy engines that are configured as TMCC engines.
Then, look at the diagram on page 3.
The WIU is not shown on any diagrams because it is always required.