The Illinois ACEP course was excellent when I did it. The set up and flow of the cases closely matched the actual exam and it even took place at the same hotel as the real thing. I'm guessing there are many similar courses out there (AAEM and Ohio ACEP ring a bell), but I'm only familiar with the ICEP one.
I was super paranoid about the oral boards, so I ended up over-preparing. I read Okuda and some other oral boards review book (First Aid maybe?), did the ICEP course, then read the books again. Just being super familiar with the flow of cases and having an internal script to hit all the easy points was probably the most helpful.