So, when I eventually got how the MOST connector block and MOST bus system actually works, it was easy.
I therefore currently have the Dension Gateway 500 installed in the car and installed on the MOST bus.
However, it does not work as yet because I need to take the car to be coded by a company who has the necessary equipment. This simply tells the CCC (head unit) to talk to what it sees as a CD changer (Dension).
To get the MOST connectors open, you simply use a flat bladed screwdriver to prise either side off and the cover comes off.
Once you have the cover open, to remove a MOST fiber, use a small flat blade to GENTLY and CAREFULLY lift the tongues in the middle which hold the fiber into the connector block, while at the samel time pulling gently on the fiber and it will come out.
I busted one of the tongues on my MOST connector block by being a little too vigorous with the tongue lifting. All I did, was swap the connector blocks over and simply used the one which was previously on top, holding the CD changer MOST BUS in and out. I was then more careful.