Like this:
|t256:128:/esoui/art/store/pc_crwn_pets_nibenaymudcrab_1x1.dds|t
(omit all spaces)
|t {width} : {height} : {texture path} |t
You can use this syntax in in-game mails, MOTD's, and in your add-ons. For example, in Tinydog's Crafting Calculator that's how I included the down arrow icons within the Add Item to Order button.
