Hi Christine,
You're right - for Step Heat, any steady state, intermediate step cardio lasting around 50-60 mins would be a good substitute (Step Jam comes to mind as a great sub).
For BodyMax, you could do any 30 min advanced step workout (CTX All-Step, maybe?);
followed by CTX Power Circuit (the leg circuits are almost identical to BodyMax's);
Then finish with a 30 minute upper body workout, such as ME upper body premix. If MM has a 30 min upper body premix, that would probably be the best substitution.
Include some abs, and you're good to go!
Cheers,
Sandra