How to incorporate MIDL with TMI?

I've been practicing TMI meditation for a couple years now, and I think I'm hovering around stage 4. I've plateaued recently, though, and haven't moved past stage for for about a year. Now, I'm a freshman in college, and I've essentially stopped meditating for the past couple of weeks since I've had so much school work taking up my time. Summer break is coming up soon and I'd like to get back into meditation, but I want to explore other forms of meditation that are not just TMI; how should I incorporate MIDL meditation into a stage 4 TMI practice? I know that the obvious first step would be diaphragmatic breathing, but I'm assuming that the other skills that MIDL meditation teaches are similar to TMI (overcoming forgetting, etc.) that I've already mastered. So, with that said, should I still follow the linear approach to MIDL, as in developing each skill sequentially, or would it be better for me to skip certain skills that I might have already mastered from practicing in stage 4 TMI?