The SLNet call that allows this is the AddElementMessage which besides creation also allows editing.
You can edit an element by assigning the correct value to the DataMinerID and ElementID properties and then configuring the Ports property.
VERY IMPORTANT NOTE: For any and all fields that you do not wish to modify, you must not assign any value to them not even null or default values.
A snippet you can use as base for your script is below but I must reiterate that these calls must be done with caution.
new SLNetMessages.AddElementMessage
{
DataMinerID = dmaId,
ElementID = elementId,
Ports= new SLNetMessages.ElementPortInfo[]
{
// Main Port
new SLNetMessages.ElementPortInfo
{
PollingIPAddress = “127.0.0.1”
},
// Second Port
null,
// Third Port
new SLNetMessages.ElementPortInfo
{
PollingIPAddress = “127.0.0.2”
},
}
}

Notice the only exception to my note above is when dealing with the ports.
If you wish to modify a port but leave a previous one untouched you must pass a null value in that array position instead of an empty object.

Disclaimer
Note that this is an internal call and we do not recommend using this, as it is not officially supported and we cannot guarantee that it will still work in the future as these are subject to change without notice. We recommend always using the correct UI or automation options provided in DataMiner Automation or through our web API.