In the root of a users profile (normally C:\documents and settings\USERNAME\ is a file called ntuser.ini. Mine has a section that reads:
ExclusionList=Local Settings\Application Data\Microsoft\Outlook;Temporary Internet Files;Cookies;History;Personal;Recent
Looks like this may do what you need, just add a folder to be excluded in...
I've not tried this myself so let me know if it works.