Assign Custom Poller

Can anyone tell me if it is possible to assign Custom Pollers with the SDK/Powershell?

I have tried using New-SwisObject as below but I get an "Access Denied" error, the user I am connecting as is an admin.

New-SwisObject $swis –EntityType 'Orion.NPM.CustomPollerAssignment' -Properties @{AssignmentName='Mike Test FW Connections';CustomPollerID='1c7b1d16-f358-4df9-b6f2-fca87050efef';NodeID='14';InterfaceID=0}

Error is:

New-SwisObject : Access to Orion.NPM.CustomPollerAssignment denied.

... blah, blah....

Is this possible like this? or by any other method? or shall I just give up? :-)

Thanks!

Mike