If you are working on a new file you can use keyswitches or MIDI controller values to switch patches. For example, you could use keyswitches for the matrix's vertical dimension (V-Span) and MIDI controller values for the horizontal dimension (H-span) or vice verse or use two different MIDI Continuous controllers for each dimension. If you already have patch changes in a previously existing score and are working in Logic you can use a Transformer in Logic's Environment to change Patch Change values into either CC values or Keyswitches. To obtain the CC values you need, simply divide 127 by the number of matrix cells you have in the dimension you wish to affect. Thus, if you used CC2 (or any other Continuous controller) to change patches in the horizontal dimension in a matrix having 3 horizontal rows, you could use values of 2, 65 and 120 to move between the cells in the horizontal row; if your matrix had 12 cells cell 1 would be accessed by a value between 1 and 10;58, cell 2 by a value between 10.58 and 20.16, etc. So, you could use values of 5, 15, 25, 36, 46, 57 etc. to access different cells of a 12 cell matrix affected by the MIDI Continous Controller you select.