CHANGING THE GENERATOR DIMENSIONS? VX ACE

I was wondering if you could change dimensions of the generator. You can resize the file but when its outputted its cuts off what isn't in the square.

The reason being is I want to experiment using custom graphics in the generator at different dimensions. It would also be just helpful if you know any alternative methods. Like, I understand you may be able to cut the pieces out and put the character together with parts. That process sounds messy though.