Hi Bob, sorry no there currently isn't any way to save construction lines to a file, right now they are only set up to exist during the current modeling session.

Also right now there isn't enough information about the construction lines accessible to scripts to make a separate scripting solution for it either.

Once v3 is underway it should be possible for me to make some more information about construction lines available to scripts to make it possible to do stuff like that though.

Currently your best bet would probably be to set up regular line objects in your template (and probably lock them so they won't be easily selectable) instead of actual construction lines.

- Michael