It's done at the end of the session, after the lifting. How or why would you possibly do 10 minutes of interval cardio between each exercise?
The rest periods in that Waterbury program are only 45 seconds and they get shorter as the plan progresses. I'm sure you can manage, at most, 45 seconds of self-discipline needed to stick to a program written by a very smart and successful coach who designed the routine a certain way to achieve a certain result.
Not to mention that, if you're doing it right and being strict with the rest periods, by the time you get to the 6th or 7th set of 3-rep deadlifts or front squats with such short rest, you'll be wishing for more rest time not another exercise to do.
Alternating cardio or "other stuff" with a set of lifting is one particular strategy, but it's not a must that needs to be done in every program. I'm a big fan of "fillers" or mobility-type work between most sets, but even that's not appropriate for every set of every workout.