Hi,

the function is located in input.wdl.

These are the lines within the function you need to modify:
force.X = strength.X*(KEY_FORCE.Y+JOY_FORCE.Y); // forward/back
force.Y = strength.Y*(KEY_COMMA-KEY_PERIOD); // side to side

You can just replace them with something like that:
force.X = strength.X*(key_w-key_s);
force.Y = strength.Y*(key_a-key_d);