I have done this on my server a few times.
You need to create a shortcut to the folder you want to give access to. Save the shortcut in a location local to the 2008 tsweb server. Then add a new application and browse to the location of the shortcut.
Make sure the shortcut points to a UNC address.
I made each folder a share and gave rights to the share at share level rights and security rights.
The folder you want to share cannot have any special characters in it.