The PS/2 end would be the same as any other k/b or mouse. As for the SDL end... Here's one for the regular Model M.

Now, I once used a Model M cable with an M4-1 and it worked perfectly, however, the reverse isn't true. From that, I'd say that the pinout of the SDL port on the M4-1 is the same, and the junction of the cable somehow splits the data line between the mouse and keyboard ports so that the Trackpoint's signals go to the mouse port, the keyboards to the keyboard port.
Anyone willing to chop open an M4-1 cable in the name of science? =P