arcpy.env.workspace
arcpy.mapping.MakeFeatureLayer
arcpy.mapping.Layer
import arcpy
topology_path = 'path1'
layerfile_path = 'path2'
mxd = arcpy.mapping.MapDocument('current')
df = arcpy.mapping.ListDataFrames(mxd)[0]
layer = arcpy.mapping.Layer(layerfile_path)
arcpy.mapping.AddLayer(df, layer)
It appears that I ran into the same question. Did you figure out how to do it using arcpy?