I understand what are you willing to do. However, I am afraid that it is not possible with RadEditor, since its dialogs cannot navigate to a different folder upon clicking on the Upload File tab.
Regarding the help file for RadEditor for MOSS: indeed it provides a link to the regular ASP.NET control, because they have virtually the same functionality. RadEditor for MOSS is a wrapper, which only provides the needed interfaces for accessing the MOSS libraries and other special features to the inner RadEditor for ASP.NET control. AFAIK there are no limitations for the full version of RadEditor for MOSS, e.g. you can use all buttons and dropdowns the regular RadEditor has.
All the best,
Valeri Hristov (Senior Developer, MCSD)
the Telerik team