Trying to set custom properties on IPs

In our organization we very frequently use custom properties in IPAM when assigning IPs. We are looking at automating the process of getting certain IPs, however we need this process to be able to set the custom values. I have currently been trying in powershell with the following, but I am having no luck. Any suggestions?

Custom Field name Device_Location

Set-SwisObject $swis -Uri 'swis://localhost/Orion/IPAM.IPNode/IpNodeId=6/Custom' @{ Device_Location = 'test5' }