Are you saying that all,the players except for the opponents goalie are on your defensive half? If so, to be offside you need to be in the other teams half of the field at the moment the ball is played or kicked by a teammate. So DO not release until!the ball is touched by a teammate. Some players will line up just inches away from the half way line ... just waiting for the through pass.

If you have the other teams defenders on their defensive half, then just like normal you cannot be behind the second to last defender at the time the ball is played or kicked by a teammate.

Soccerref

Yes like that. However this doesn't explain the rule. Torres received the ball in his teams defensive side of the pitch here in this instance. But could he, when his team gained possesion of the ball, gone across that half way line with the Barcelona defense pressed so deep into Chelseas defensive side, and been onsides after receiving the ball, running accross that line upon Chelsea possesion of the ball? That is my question, with defense pressed that deep, at what point can he go across the half way line and still be onsides, with defenders that deep?

I think JETSMR's video explains it. You can't be offside if you are in your own half when the ball is played to you.

If i am understanding correctly I think this is the situation you are explaining. This Chelsea vs Barcelona goal should answer your question.

SKIP to 1:17 that is the situation your talking about i think.