1. Work on compression for L-sit and straddle-L everyday. After a couple months in.. everyone can handle this.
2. L-sits/straddle-L 60s for the skill work every 3-4 days. Once they can do either in one set that's great... then maybe go for the 90 or 120s.
3. Start integrating manna at the MSH variation once you have a sufficiently developed straddle hold. I don't like starting it before then because you need more equipment, and people will try to get ahead of themselves.