Ah, it actually is documented in the pdf I linked, just hadn't noticed it:

Note1: The Select New filter command will always rotate the filter wheel in a
clockwise direction to arrive at the target filter. If 128 (0x80 hexadecimal) is
added to the “New Filter number” then this will allow the filter wheel to
rotate the wheel in either direction to reach the target filter in the shortest

I added unidirectional movement as an option, will submit a pull request after some quick testing.