Well I think I can explain the other part fairly shortly and you should understand. You can lure any of the first five guards you encounter to go to the glass by using the stone door just like you use the mainframe. Have the guards see you by the open stone door, close it and run fast to the glass, stay there for a while, depending on how safe you want to be, then hide behind the console or mainframe and they will run to the glass if done right.
The problem with this is that I think it takes the guards too long to run there, I could be wrong though.
However, I believe if you do this, then bring the mainframe guard to the glass, he could open it by himself. Reason: weve seen one guard open the glass all the time, he just needs other guards that want to get to the same spot as him.