Hi, Steve,
First, put your macro in a module in a separate template -- you don't
want to do this to your Normal.dot. (You can only lock out a whole
template, not an individual macro or module. Besides, you should have
a separate template to distribute the macro -- see
http://word.mvps.org/FAQs/MacrosVBA/DistributeMacros.htm.)
When the macro is complete, go to Tools > TemplateProject Properties
and click the Protection tab. Check the "Lock project for viewing"
box. If you really don't trust people, enter a password. (Hint: since
you probably won't remember the password after a few weeks, be sure to
keep an unprotected copy of the template somewhere safe.)