The description, in the MR816X/CSX manual, on how to access the hardware controls is useless for anyone using Cubase 7 or later.
Here’s where you find it in the MixConsole. At the top of the “Chanel Racks” a new “Hardware” rack should appear, containing the hardware controls:
In case you don’t see this rack, make sure that “Hardware” in the “Racks” menu is checked:
Hope this help you save some time searching.