To be able to perform the desired modifications, we first have to place the Macbook Pro on a soft surface (to avoid scratches of the aluminum finish) and the bottom side facing up:

After removing the 10 tiny Phillips screws, the bottom cover can be raised, for revealing the internals:

The area we are now interested in is the one with the optical drive; this must be removed in order to install the MCE OptiBay:

With a plastic spudger tool, we must first remove the two data and power cables that are fixed onto the PCB (we do not have to apply a lot of force when performing this operation and must be very careful not to touch the lateral SMD components:

Another cable coming from the Wireless and Bluetooth module must be removed in order to access the first Torqx screw which holds the drive into place:

The module which we were talking about before must also be removed and is held two extra Phillips screws (one longer than the other):

Finally, we have to remove the remaining two Torqx screws residing on the left side; then we can lift carefully the optical drive assembly, without touching any other components: