Limit quantity of attribute?

I tried searching the forum, but the threads either didn't have replies, or it didn't answer my question.

So say I sell t-shirts in my store. I have attributes set up for the different sizes: extra small, medium, large, extra large in a drop down menu on the product listing page. Now, is it possible that I can restrict each customer to only only buy one extra small, but unlimited quantities in the other sizes? So essentially, I have limited stock of XS, and to avoid running out, I want to limit only one XS per customer.

Thanks! Any help is greatly appreciated. :)

Hey there. I figured it out for you as I needed this functionality as well. Go into your product for xs shirts. Enter 1 as the products qty maximum. I tested it with my cart (I don't have attributes just yet but I'm hoping this will work for you as well) and when I tried to put a 2nd one in my cart gave me an error stating that I'm only allowed 1.

Hope that helps.