Toralfsens suggestion with the red arrow does not seem to work on my BV7.
The main reason I would like to operate the tray from my Beo4 is that I have a young child and I don't want her to play with the tray. In the DVD service menu I found the option "Block Sensitouce": YES/NO. It blocks the eject/load button next to the tray and makes an alternative highly needed.
If I press DVD with no disc in an open tray, it closes, tries to load the disc and then ejects again asking for a disc!
I have found no way at all to eject neither with or without disc.