Cabinet making: How to link part dimension to a sktech in an assembly?

Hello, I create a parametric cabinet libray using global variable and configuration.
I would like to link them to a 3d sketch on assembly level as per this video: https://www.youtube.com/watch?v=JzwvMrofZ2Q
But I have no idea how to make the global variable driven by the sketches, and I'm even not sure that it can be done this way.

Another approach is to used smart component as per this video at 7min43s : https://www.youtube.com/watch?v=zEKvK-0R6p4
But again, I don't know how to achieve this using my parametric cabinet multibody part.

If somebody knows how to get this done, could you please take the time to explain the process. Thanks