If all you want to do is edit the PATH to the My Document folders, then you just need to follow Enablingwolf's suggestions. AFA the Registry edits he pointed you to in the second link he provided...you can edit the path's by editing the String Value Names in the Registry under the following Key (just as the link that he provided explains)...
HKEY_CURRENT_USER | Software | Microsoft | Windows | CurrentVersion | Explorer | Shell Folders
If you wanted to modify the path to the My Pictures folder for example, you would need to right click the "My Pictures" String Value in the RH pane...and select "Properties". In the "Edit String" window that opens, change the path to the My Pictures folder by editing the "Value data" field.