So here’s a tutorial for modeling in lithtech engine; Moddb.com
you will need Milkshape 3d,Blender,ModelEdit,ABCD tool and DEdit.
Blender will be used for general model editing while Milkshape 3d will be used for rigging the model to the skeleton(note you need to separate model into different pieces in blender).Once the model is done open the model in ModelEdit and see if everything is ok after that you need to open the ABCD tool and decompile you’re model to reset the skeleton.This will create the model in LTA format open the model in ModelEdit and save as ABC and you should be good to go