I've been wondering if this was possible, so many thanks Paul for
answering Rhonda's question.

I had to make one change to the code  to get it to work in Excel 2007.
I have no idea if they are also needed in Excel 2003. This was to
make the last line (before the End Sub):
ThisWorkbook.VBProject.VBComponents.Import Filename:=ModFileName
rather than
VBProject.VBComponents.Import Filename:=ModFileName

I have also found that you can then automatically run  the macro  that
has been created using
Application.Run "EnterText"
where "EnterText" is the name of the subroutine.