I cook turkey tenderloins every once in a while. Here is an injection recipe that I use:
1 cup of white wine
1/2 cup of fresh squeezed and strained lemon juice
1/3 cup of honey
1/3 cup of butter/oleo
Heat ingredients until the butter melts. Allow solution to cool before injecting. Use no more than 1 ounce per pound. Due to the acidity of the solution, do not inject more than four hours before cooking. This solution works well on whole turkeys and pheasants as well. I like to use a light coating of rub on the tenderloins.
Cooking temperature is up to you as well as the wood you use for smoke. I like peach or pecan. If you are cooking 250ºF or below, remover the tenderloins when they reach 162ºF. If you are cooking hotter than this, take them off when they reach 155ºF. Let them rest for 30 minutes under a foil tent before slicing them across the grain.