We just did this a couple of weeks ago for Crystal Palace - you will need to give yourself enough time to get through baggage check and then you will get in line (it is the same line for all early ADR's, Tours, Etc.). This year it is to the far left (2 years ago it was to the far right), but it should be the only line unless there are extra magic morning hours. They do not check your reservations/name at Magic Kingdom - they did at all the other parks though.
They begin letting you into the park at 7:45/7:50am. Be sure to check in right away, regardless of what time your ADR is (unless it's like 9am or something and at that point they might not let you check in yet), but if you have something before 830am, try to check in as soon as possible. Most people don't check-in right away, but they generally seat you in the order you check in. We had an 805am ressie, but the check-in line was quite long, so we wound up not getting seated until after our ADR time. There were people in front of us in line with later ADR times that were seated before us. I cannot complain because we have been in the same boat - an 8:15am ressie and seated 4th at 8:05am
). My question is how do you go about doing this? Do I need to show a CM proof of my reservation? Is there a special entrance I go to? 
