Pole Target in Python

Hi, I am trying to set pole target using python. I could successfully setup IK constraint, but did not find anything on setting pole target. Can some one please help me in doing that?

ArmPose=ArmObj.getPose() 
CBone = ArmPose.bones[CnsBoneName] 
CBone.constraints.append(Constraint.Type.IKSOLVER) 
cnslen = CBone.constraints.__len__() 
cns = CBone.constraints.__getitem__(cnslen-1) 

cns[Constraint.Settings.TARGET] = ArmObj 
cns[Constraint.Settings.BONE] = IKBoneName 
cns[Constraint.Settings.CHAINLEN] = ChainLen 
ArmPose.update()

you made it nearly the same way i did, and my script works,
that what i made different

maybe you want to use the end of your posebone:
cns[Constraint.Settings.USETIP] = True

i also set the influence of the constraint and set the IPO for the Influence
cns.influence = 1.0
cns.insertKey(frame)

at the end i make an update:
armObj.getPose().update()
scn.update(1)

as far as i remember the scene-update starts the recalculation of all IK-Solvers