Unique Ring inbound DID

I’m looking for a quick solution to a task, if possible. I have a FreePBX system setup, stable for the past year, so I don’t want to rock the boat too much if I can help it, but a new requirement has come up. We’ll be moving the company into a location where the PBX system can easily act with the bulk of calls to my phone numbers being handled through the auto attendant. But I would like to have calls to a specific number or 2 ring with a different ringer on my phones. We’ll be migrating all to Polycom variants, mostly VVX400/410s or 300s. Is there an easy solution to enable a single unique ringer for the new DID? I’ve added an alert phrase but having troubles safely inserting the code that others recommend. Does FreePBX have a quick step guide somewhere for this?