You want to first match the level to the amp powering the coaxials. Do this by adjusting the gain so the overall sound is balanced. (Microphone and roomeqwizard helps here)
Set the crossover point somewhere between 80hz and 100hz. It doesn't have to be exact. You can play around with it later.
The phase should be set to 180 degrees. Don't need to mess with that at all.
Extension and damping are just personal preference and you can use the eq to take care of peaky bass.