– Nothing to say here, this should be quite easy to do 😀
Prepare the retainer with two M5x8mm screws and two M5 t-nuts.
Mount the retainer on the left channel of the right z profile. The screw holes are slotted so you can move the mount slightly to left and right. Place it so the top of the retainer is slightly higher than the bed. You might have to adjust this position after you did the first homing. If you’re using the Probe as z endstop even the z_offset will affect the height of it.