Volume for individual pickups...blending?

I'm very new to how pickup wiring works. I recently had a couple humbuckers installed with very simple wiring/pots. I just have tone and volume for both pickups with with a 3 way switch so I can have individual pickups or both at same time. I am wondering if there's a way to control volume for each individual pickup so I could dial one in more and/or take out some of the other... Is this a big mod, what would be involved? I'm hoping its just a matter of having another pot/knob added but I'm also considering having it re-wired and trying some split-coil scenario since I'm not totally sold on the tone I'm getting. Basically I love the bridge pup tone but want to add a little bit of the neck pup.

 

Is this the type blend pot you speak of? BOURNS 500K Split Shaft Audio Pot Potentiometer Blend Balance NEW Guitar Part | eBay

And that could just replace the 3 way toggle switch? Sounds like it would perform same function but I can blend them? thanks