I remember that a while ago, in the Q&A, they said that if you
- Start in the opponent’s courtyard
- Go through a category C defence such that you are fully contained by the neutral zone but are still holding open the defence
- Break contact with the defence
- Catch the door before it gets back to “resting” position
- And go back through the now-open door from the neutral zone to the opponent’s courtyard
It counts as a crossing. However, I never saw this utilized at the week 0 competitions. Was this just happenstance, or has it been made illegal since that Q&A question?
This maneuver is little more difficult than it sounds when you are using the official field. The lexan for the drawbridge is very flexible compared to a sheet of plywood in the the team version.
Its possible but would need to be fast and clear enough for a referee to see you are following the steps of crossing properly.
Keep in mind that most Week Zero teams (like ours) were using mechanisms we only got working the night before with no drive practice so getting fancy on the field was low on our priority list. 
See 3.1.3, especially the Blue Box text beginning, “If it is unclear … .”
Referee training includes some examples. Referees are instructed that in most cases they are to give teams benefit of the doubt when a scoring call looks close; however, in when it is unclear whether the robot has satisfied all the requirements for CROSSING or REACHING a DEFENSE, they are instructed not to enter scores.
If you’re planning on doing this, you might want to consider notifying the refs before the match and/or doing the maneuver two or three times and spend those extra couple of seconds to make sure the refs spot what you’re doing.
What he said, plus you might want to install LED’s on your robot, and flash them when you are about the perform the “Tap” maneuver.