The best practice is to assign an alias when first creating the toolbox rather than using ImportToolbox to assign a temporary one that will only be applicable in Python.
arcpy.ImportToolbox(r"x:\MB_Svenne\AutoRun.tbx", "TBX")
# Calls a model called Test (with no parameters) in a toolbox with the Alias set to AUTO
arcpy.Test_AUTO()
# Calls a model called Test (with 1 parameter) in a toolbox with the Alias set to AUTO arcpy.Test_AUTO(r"c:\temp\clipPoly.shp")
resObj = arcpy.Test_AUTO(r"c:\temp\clipPoly.shp") if resObj.status == 4: print "success!" else: print "failure :("