Both solutions do not produce equivalent output. I converted nullus's routine to asp:

function DateToNum(dtDate)
Dim lngDate
lngDate = CLng(CDate(dtDate))
DateToNum = lngDate
end function

however this gives me 25569 for 1/1/1970, while the authorware routine returns 25568.
inserting "June 2, 2036" returns 49828 while in authorware it returns 49709.