Depends upon the specific type of finings that you're using; the instructions are usually on them. Some should be rehydrated in sanitized water before adding to the fermenter and some should be specifically rehydrated at low temps.
It also depends upon whether you're talking about Kettle Finings (added during boil so obviously no stirring required), or finings that are added to the fermenter (might want to stir)
Stirring is not necessarily bad; it's oxygenation that's bad, as long as you stir carefully you won't oxygenate much.
If you're adding finings to the fermenter after fermentation is complete then you're not stirring wort, you're stirring beer. <!-- s:) --><img src="{SMILIES_PATH}/icon_smile.gif" alt="

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(Hot-side aeration is generally more of a concern than cool-side aeration, too.)
Adam