The same way that you can install "Bass Blockers" on your tweeters, you can bass block your midbasses. For a 4 ohm speaker, and ~80 Hz corner frequency... a high pass filter can be made from a 500 uF capacitor.
LINK to Parts Express
If there are other crossover components, they may interfere with operation... higher order options can be made without too much headache too.
Calculator:
LINK