Code to Force Format / Prevent Format Changes

Ok I've done this before so I know it's possible but I can't find my code so I hope you guys can help me out. I have report that people are going to be pasting data into. I want the destination formatting to override the format of pasted data. Now I know that you can just paste special or maybe double click in a cell and then paste. The problem is that I am working with very entry level excel users so I can't count on them know or remember that. This is excel 2007. Any help you could give would be appreciated.

Thanks,

-Michael