Here is my super mini tutorial if needed:
Trinity has to be set to identify legendaries for these rules to work.
Download the zip. Unzip the folder. Put it anywhere, it doesn't matter. The world is your oyster.
Go into Trinity settings, under "Items -> Pickup" set "Choose Item Rules Type:" to "File Based Script Rules"
On the "ItemRules" tab set "Use Rule Set:" to "Custom *RTFM!"
Set "Optional Custom Item Rule Set Path:" to the location of that magical folder you downloaded. Hit "Reload Script Rules" for good measure and you should be good to go. You may want to go to the "Town Run" tab and set it to salvage legendary items, as vendoring them is rather wasteful.