Having gone through the same, I would firstly realize that it's ~90% overlap with McKinsey Operations and 75% overlap with McKinsey generalists. So although the websites etc, will highlight the differences, the roles are in fact much more similar than they are different, and therefore you should be practicing the same overall skills and interviewing techniquest.
That being said, the focus is slightly different. For implementation, you should be thinking a little more about how you achieving impact through both people and organizational change. Highlighting leadership ability and getting people and organizations to move outside their comfort zone is key. Of course all consultancies value this, but it's weighted slightly hired at MI.
Happy to share more. Just ask. In the meantime, hope this helps!
Best,
Allen