You can leave out this steps with disconnecting the two cables.
Without disconnecting the two cables, one can separate the two pieces only 1/2 inch. This is enough to work carefully with the soldering iron and change the battery.
It's a little bit difficult to work with the needle to open the three holes after removing the old battery - but you can do it.
From the reading of the other notes it seems to me easier than to disconnect the two cables
I changed the battery yesterday and left out the steps 7 - 9. It's not really necessary to seperate front and back completety.
So you can't break the brown tab. :-)