Most likely Nobody is responding because you should be asking a question about editing in The Lancers Reactor > Forums > Freelancer Editing:
Freelancer General Editing Forum
And or reading about how to edit characters in The Lancers Reactor > Forums > Freelancer Editing:
Freelancer Editing Tutorial Forum
I'll try and answer your question for you here anyway......
Download the
Freelancer SDK v1.3 and install it into a folder of you choice and you can also install it right into the Freelancer folder.
After you install the Freelancer SDK version 1.3 navigate to the Program Files\Microsoft Games\Freelancer\DATA\CHARACTERS folder and look at bodyparts.ini and costumes.ini
Those two files should be the files you need to edit.....