According to steam forums. "No" since steam has its own launcher and way of linking. Origin Downloads or so cant work on steam base. (Or Physical copies it seems) So steam has to run with steam bought sims 3. HOWEVER you should be able to right click Sims 3 in your library, get the cd key. Redeem it on the website and have a origin copy. Then you can link all these to that. Most people use Origin for Sims 3 so its easier to use the Sims Store for stuff.
~Battlez-avec la Mystique?~