I don't think the BLU PCC will work with any manual battery. For a start the manual switch itself would negate inserting one and even if you could, it would effectively be always on, since the switch would need to be constantly pressed to fit in the PCC. Be careful filing those cartomizers. Auto batteries really don't like getting liquid in them, as I fear you've found out.
The BLU does what it says, imitates a cig and expects you to always do what BLU cig wants which is buy their carts and their parts and effectively throw away stuff when they run out, it's expensive and when you do try your own thing, you'll likely see the short comings in the BLU more and more. My advice, and you might not like it, keep the BLU as a back up and look at a cheap eGo / Riva / 510 Titan style starter kit with manual switches. It might seem expensive (though I personally thing not myself) but it's worth it in the long run when it comes to delivery methods (cartomizers, clearomizers, tanks etc) and your own liquids without fear of wrecking a battery.