[Zope] Nightmare - Locked myself out (with SiteAccess). How to get back in ? back in ?

[chas]

Being the silly bugger I am, I put a SiteAccess Rule into
the root folder of my development Zope server and now can't
get back in at all. Is there any way to force undo the 
last change ? I've tried deleting the 'access' file or
setting its contents to 'admin:' with no password but
neither succeed. This is on NT.

To say that I'd be extremely grateful for any help getting
back in, would be a vast understatement :)

chas