This Ikea hack is very simple.
Mount the Kallax shelving unit as per Ikea instruction.
Before to mount the last shelf on Kallax structure, mount the wine glass racks, in this way it will be easier than do it after (image n.9)
As you can see from image I left the upper side open to fit a microwave oven.
If you wanna left same “empty space”, simply do not mount last vertical square as showed on images 10, 11, 12, 13 and 14 (they comes from Kallax’s assembly instructions).
When Kallax shelving unit is complete, insert the doors and wine bottle rack.
Finally mount the LED light strip vertically on the back and enjoy.