Cutting cold butter into flour - which mixer attachment should I use? I have a kitchenaid 6 quart stand mixer and a large family of nine.  At the moment we're using coupons to buy biscuit dough, but I wanted to look at the time and effort to make our own.  Not just for cost savings (though that would be nice) but more to control what we're actually eating.

Many of the better recipes call for the butter to be cut into the flour.  I have a hand tool for this, but am unsure whether the paddle or whisk is best, or if there's another tool I should consider purchasing.

What tool should I use, and at what speed will best duplicate the process of cutting cold butter into flour without warming up the butter too much?
Since you ask about other tools, I recommend avoiding the mixer altogether and instead grate frozen butter into the flour. If you have a food processor you can use the coarsest grating blade--chilling the bowl and grater first will help keep the butter cold will help--but it goes quickly by hand with a coarse grater.

The key is to get the butter distributed quickly and keep the butter and dough cool while working the dough as little as possible. If you do use the mixer, chilling the bowl and paddle helps. 

And, regardless of method using ice water and very cold liquids helps.