1. Copy "C:\Users\<Your windows username>\Documents\Elder Scrolls Online\live\AddOns" folder to "C:\Users\<Your windows username>\Documents\Elder Scrolls Online\pts\AddOns"
2. You may need to add the .exe for the PTS launcher in Minion but that's what worked for me.
That's all.
To point 1:
If you play on the EU servers just switch "live" to "liveeu"