Yes I was doing a hybrid of Crossfit workouts and Maximum Effort training (3 sets of 5 reps in squats and presses). I tried to hand-pick the WOD so that they were not full of pushups. This way I could sometimes do the pushup plan as part of my warmup. Also, doing them at the end of max effort training seemed to work well. I think you could make it work as long as you don't do too many Crossfit workouts that contain a lot of pushups.
I can't emphasize enough how motivating it is to KNOW you have to do at least one more pushup than you did last time. Without that, I would have quit a lot sooner on just about all of my to-failure sets.