First of all, I have explictly not done this as I wasn't sure if I was edging on breaking the rules.
If you are in a situation where you are playing a game and you are going through lines at is in the game in progress that is still within various database games.
You are looking along lines in GM games and you do an engine analysis on the database game so you can note possible lines that are several moves ahead of your actual game, but in the DB game. Is this breaking the rules? After all, you aren't calculating on your current game actively at the current move. I am presuming it would be against the rules because in the process of calculating the DB game, you would have incite into what moves to make in your current game.
The grey area could be that you are playing various games in a certain opening, and away from RHP you could be calculating various database games with that opening, yet you could still remember the results from this when you come back to RHP.
I certainly have done engine analysis on games I have completed, along with the DB games, but not during the game.