In that one template, create a macro like this (substituting your
folder path in the quotes):
Public Sub FileSaveAs
With Dialogs(wdDialogFileSaveAs)
.Name = "c:\windows\temp\"
.Show
End With
End Sub
The special macro name FileSaveAs means that the macro will be
executed whenever the user selects the Save As command on the File
menu. Other variations on this theme are described at
http://www.word.mvps.org/FAQs/MacrosVBA/ChangeSaveAsPath.htm.
If you need instructions for creating the macro, see
http://www.gmayor.com/installing_macro.htm.
The general idea of using macros to intercept built-in commands is
discussed at
http://www.word.mvps.org/FAQs/MacrosVBA/InterceptSavePrint.htm.