Erm... You can technically RUN it, yes... but it's going to be a rather shitty setup.
If you don't already have the 660s, can I beg you to spend that money in a better way? You should NEVER crossfire/sli low end cards like that - it causes way more issues than it's worth, and the performance isn't very good.
Why spend the money on two 660s and a 470 when you could buy a 670 for cheaper that would outperform the three cards, not have any microstuttering, AND would work in every game, instead of having to pray that the game supports SLI?
(Because I mean, look at it this way. A 670 will always work and give great performance. In a game that can use both Physx and SLI, then you're in decent shape with the three card setup, IF you can figure out how to keep them cool. However, in a game that doesn't support those, a 670 still gives you good performance, while a three card setup gives you the performance of... a single 660. Most of the time you'll have two thirds of your graphics horsepower just sitting there doing nothing.)