Using Office 2003 and Windows XP;

I am developing a form for wide distribution that will be locked down fairly
well. I know anything can be hacked, the sole purpose is to discourage casual
mistakes and tampering that would generally compromise the programming built
into the form.

However, I need to build myself a back door into the form that will unlock
everything and restore certain menus that will be controlled, etc. This is
needed so that myself and another developer can periodically perform
maintenance on the form. I already have the unlocking code written, but what
is a good way to access it without a user stumbling onto the key?

Does anyone have any suggestions for how to "back door" my way into my own
locked down form once its placed into production?

All suggestions welcomed, please respond...thanks in advance.