Experiments to determine the effects of therapeutic shoe outsole modifications frequently require the examination of many different configurations and typically use in-shoe pressure measurement to determine the optimal design. A method is presented here to allow the foot-shoe interface to remain undisturbed as different outsole designs are used in the same patient. A standard extra-depth (or super extra-depth) shoe is modified to house three receptacles for quarter-turn fasteners in a carbon fiber plate. The fasteners pass through the outsole unit and secure it firmly to the plate. Results from a typical experiment are presented to illustrate the effectiveness of the approach. It is possible that a large clinic could use this approach in complex cases to assist with optimal footwear prescription.