It's very simple to do yourself, by editing just a 1 line of code in the common.asp file to read in the NT user password instead of the cookie then place the NT user password in the tblAuthor in the field storing the users usercode.
Below is the code I use for this perpose:-
'Read in users ID number from the cookie
'strLoggedInUserCode = Trim(Mid(Request.Cookies("Forum")("UserID"), 1, 44))
strLoggedInUserCode = Trim(Request.ServerVariables("AUTH_USER"))
I also wrote a new signup page that simply placed the NT user password in the usercode field.