Well, if you know what you are doing, and do it carefully, you can add new pieces to a preset. You would have to make a copy of the moves of the Sergeant:
and copy that to the end of the legdefs table, behind the King moves. Then you would have to change all the y steps there (the 4th number on each line) from 1 to -1, to make it move in the other direction. Finally you would have to calculate where this appended section starts, which is 8 lines of 5 numbers plus the terminating zero (i.e. 41) places behind the King (which starts at 5703, as the comment indicates). So it starts at 5744.
Finally you replace the 5616 in the line
def sg cond #0 5616 0;
by this 5744, to let the GAME code know where the moves of the black sergeant (sg) start. That should do it.
Well, if you know what you are doing, and do it carefully, you can add new pieces to a preset. You would have to make a copy of the moves of the Sergeant:
and copy that to the end of the legdefs table, behind the King moves. Then you would have to change all the y steps there (the 4th number on each line) from 1 to -1, to make it move in the other direction. Finally you would have to calculate where this appended section starts, which is 8 lines of 5 numbers plus the terminating zero (i.e. 41) places behind the King (which starts at 5703, as the comment indicates). So it starts at 5744.
Finally you replace the 5616 in the line
by this 5744, to let the GAME code know where the moves of the black sergeant (sg) start. That should do it.