The only solution i can see for targeting a pet tank in EQ1 would be if the character purchased a potion of pet amnesia from the marketplace, once a name is chosen it will remain the same for all pets he/or she summons in the future. Then its just a simple social for /target "insert name here". My main character is a Magician and named my pet for just this reason. I normally run 4 mages a bard and a necro.