A chinese photographer reworked the Sigma DP1/2, he removed the fixed lens to add a lens mount (The picture shows the Sigma with the Leica Elmarit f/4 90mm). According to the author:
1. He can put a M4/3 mount on it, then you can use mount adapter to convert to other mounts.
2. The author had tested drive an additional mechanical shutter to replace the original electronical one. He is ording parts from a Japanese factory.
3. The author vaguly mentioned possibility to drive AF lens, I don’t know if he/she had done any prototype or it is just doable.