Were Ellen Barkin's legs highlighted or enhanced?

I am quite certain it is just her legs. She "walked like a man¹" which would most like cause her to walk different. The fact that she is seen in a skirt throughout most of the movie just accentuates her legs.

There doesn't appear to be a lot of special make-up effects, other than basic make-up, costumes, and the like. This is just a man that got put into a woman's body, not much more magic to it than the cast, the costumes, and the script.

Here is a picture of her legs in Bad Company, a different movie than Switch:

^{As you can see her legs show some definition.}

Here is a picture of her legs in Switch:

^{Actually, there appears to be less definition in her legs. That may be what you are attributing to be as more manly.}

¹_{Not Your Average Male}