I went through this last summer for my 2006 Meridian. I went on ebay and found this pigtail:
Freightliner XCM RV trailer brake harness Winnebago Newmar pigtail wiring plug
I texted the fellow that has this listing and he had all the answers. I told him what controller I had and he wired the pigtail with the same colors my controller used, no brainer at that point. Like mentioned before, my connection was to the left of the steering wheel, it was even labeled trailer brake . The ebay listing has a picture of the connection.
By the way you can get the same pigtail from Freightliner but you'll pay three times as much.