want to change my 2 band to 3 or will this switch do the trick

i love my bass a whole lot but there is one thing i really want to change in it. it has alembic pu's and electronics on it, but with 2 band. how could i put a 3 band in there? would it be too much trouble? how much money would something like this set me back? in the electronics cavity there is a little blue switch thing. can this tweak my mids? ok, thanks, ryan