Greg,
I'm glad you asked this question and this is something I've been thinking of for awhile. Here is what I would do;

Week I

Day I

ME Squat/DL

Day II

ME Bench

Day III

DE Squat/DL

Week II

Day I

DE Bench

Day II

ME Squat/DL

Day III

ME Bench

and so on...

What I think this can do is allow your body for more recovery, allow for more volume during your workouts and keep you fresh. Many times, during the 4 workouts/week, you end up taking ME days or doing repetition work. By doing the 3 days/week workout, you can avoid this. Try giving this a shot and let us know what happens.

Give it a shot,
Jim Wendler