B.P.
In addition to whatever else you decide to do, here are some suggestions:
-Try putting her in clothes that make it harder for her to get her hands in her pants (ie tighter jeans rather than loose, stretchy pants). That way if it is just a habit, she will be less likely to do it. Of course this will probably be harder to do with the warmer weather coming up!!
-Keep her hands busy with other activities.
-Every time you see her with her hands in her pants (or nose), send her to the bathroom to wash up. They usually get the point pretty quick because they get so tired of washing their hands.
Good Luck!