Hi Schizo,
you can see the location of assets by clicking on a resource in the
content browser and checking the "source file" property there.
The correct way to mod these is by putting your customized .gr2 file in your own mod (e.g. Data/Public/ShizosMod/Assets/Characters/Lizards/Lizards_Male/SHIZO_Female_Skeleton_A_Body_A.gr2), then opening that mod in the editor and overriding the resource you want to change by changing the source file property on it to your custom model.
Hope this helps!