You could do what 90% of the people here do and set it by ear.
Or you could read the
Gain Setting Tutorial for the DMM method. Which is a sticky I might add.
The bass boost is easy, set it to 0. Subsonic is also pretty easy, just set it 5-10hz below the tune of your enclosure. If you hear the woofer making mechanical noise with low notes (below your box tune) turn it up more. LPF can be different depending on how high YOU like your sub to play, most people just set it between 70-80 hz. All this can be found numerous times via the search bar in greater detail.