was wondering if this was possible or is eventually a planned feature?

the program seems great as of right now but just lacks the customization that i'd want (at least i'm too blind to see if it's already implemented) out of a program such as this and was wondering if there are plans to implement more user based customization

I second this sentiment

You can already implement your own custom items into the kit and replace things with your own stuff. Just click on the star and add own clothes etc. 

Idk if the jiggle update is already out but with that you could even bring your own hair into the kit. 

As battlesheepy said, you can now do this with the custom jiggle items. Import your own hair, pin them to existing hair, and then check the box to turn off the original sprite. It's not going to be perfect but it works well enough. Unfortunately with the way the program is set up, that's the best we'll probably get.