Mesh listener setup snippet from Tom Dymond, posted on Foundry coding slack channel.

meshListen.py

import modo, lxifc

geo  = modo.MeshGeometry("Cube").internalMesh
port = lx.object.ListenerPort(geo)

class mesh_listener(lxifc.MeshListener):
	undoService = lx.service.Undo()
	def __init__(self):
		self.listenerService = lx.service.Listener()	
		self.COM_object = lx.object.Unknown(port)
		
	def ml_Changes(self, event):
		print "change"
		
l = mesh_listener()
port.AddListener(l)