First thing is, if the injury is not fresh, poltice is not going to do what it is intended to do. poultice draws heat, that is its only purpose. So unless the area is generating heat, there is no point.
What I do before i poultice anything is cold hose it for 20 minutes or so. The stifle is going to be a hard area to wrap, so I would go with a product called "Stay Sound". It is basically poultice, but you don't have to wrap over it. If you use regular poultice just cover the area with about 1/2 inch layer of poultice, then wrap the area with a WET brown paper bag, then use a regular wrap over that. If you don't use the paper bag you are going to ruin your wraps. I will take the wrap off the next day, cold hose the area(which cools it but also cleans the poultice off, which gets hard and crusty and sticks to the hair) and then re-do it as necessary.
Good Luck!