Cropping charset pictures into one single actor.

If anyone has used the Sideways Battle System 2.7, you need to have an actor that has their character graphic (the one that moves around on the map, not the faceset) to be singular, showing only the actor themselves, instead of the usual sets that have 7 other characters on them.

My main question is that, how do you crop the pictures perfectly? Is there some sort of trick, method, or application that aids me in this? Or do I just have to do it by hand? Because I tried that, and the character ended up a bit to the side and their background was completely black.

Anyone that can point me in the right direction on this, I'd appreciate greatly.

Use the original character sets given as a template, and simply put the desired sprites over it.
Then delete the original.