For Softimage. This script gathers all the polymeshes for selected models and places them in model-specific groups.

softimage_GroupMeshesByModel.py

# Gathers all the polymeshes for selected models and places them in model-specific groups
# (i.e. one group for each model).

from win32com.client import constants

if len(Application.Selection) > 0:
    selectedModels = [item for item in Application.Selection if item.Type == '#model']

    # Create the groups and populate them
    for model in selectedModels:
    	flag = True
    	for group in Application.FindObjects("", "{9D0673C2-6741-11D1-BE9F-00A024EE478D}" ):
    			if group.Name == "%s_POLYMESHES"%(model):
    				flag = False
    	if flag:
    		grp = Application.ActiveProject2.ActiveScene.Root.AddGroup(None,"%s_POLYMESHES"%(model))
    		for mesh in model.FindChildren("", constants.siPolyMeshType, c.siGeometryFamily, True):
    			grp.AddMember(mesh, False)