I have the same question. Did you ever figure out how to do it?

Nope, tried Reddit as well. No luck.

damn, I'd really love to have this, but also the option the customize as I please. seems there's no way other than manually.

There's this mod, but I haven't tested it myself yet:
(Let me know how it goes.)

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1455811827

the armor upgrade normalized seems a bit of a hit and miss for how it was configured. ive got it myself but never modified it yet but the way i understand it, in the config of the normalizer, it defines what body part it came before and what it would look after the upgrade, so assuming you want your custom characters to have a new predator look, you have to first define what they look like as kevlar exactly and then proceed to define what they would look like as predator or even spider. in paper this is a thousand more configurable, just a bit tedious if you have a bunch of unique characters you want to have different upgrade "paths" separate for the entire group. this also becomes VERY hard if you consider that it may also cause randos picked from scans or bought to not have their own generic predator look. ill look into how it actually work for myself and tell it here.