Schoeps' main "Double M/S" recording system uses a single, sideways-facing figure-8 plus two cardioids. One cardioid faces forward while the other one faces backward; each cardioid forms an M/S pair with the shared figure-8. The shock mount in the photo is designed so that the centers of the three capsules' membranes will all line up vertically. Since a figure-8 pattern is symmetrical in three-dimensional space, the top surface of the capsule can face forwards toward the center of the sound source(s) while the capsule's main axis is pointing left and right.
It is also possible to use a supercardioid (e.g. a Colette-series microphone with the MK 41 V capsule or the equivalent CCM) for the front-facing microphone--or even a shotgun mike as their Web site shows. But their VST software plug-in is based on the specific characteristics of the MK 8 and a pair of MK 4Vs.
As someone pointed out earlier, a similar thing could have been built around an omni with two figure-8s, given a slightly different approach to the signal processing. But essentially the same audio information can indeed be obtained that way.
--best regards