The short answer is I'm not sure
,I have tried but can't find a way.
But I think we should have an option in the 'Save as' dialog to save any drawing (including an existing template) to a dwt (drawing template) where we can choose our own template name and destination
A feature request is needed
EDIT: Feature request added:http://www.qcad.org/bugtracker/index.ph ... ask_id=868