Force a specific time in this vCalendar code...?

I use the vcalendar code to send an appointment from a webform.  How do I use the code below to always have the time set to 8:00:00 am?  So if a user only puts in a date, the code will make sure the appointment is set to 8am.

' Get the start and end dates of the event (GMT).
startDateAdd = request.form("startdate")
endDate = request.form("startdate")
 
' Get a unique ID to assign to the calendar event.
uniqueID = FormatDateTime(Now()) & "-" & tmpName & "-@" &_
   Request.ServerVariables("SERVER_NAME")
 
Set file = fso.CreateTextFile(filename)
 
' Write the iCalendar file to the file system.
file.WriteLine "BEGIN:VCALENDAR"
file.WriteLine "PRODID:-//ASP iCalendar Test//My ASP App V1.0//EN"
file.WriteLine "VERSION:2.0"
file.WriteLine "METHOD:REQUEST"
file.WriteLine "BEGIN:VEVENT"
file.WriteLine "ORGANIZER:MAILTO:" & Session("MM_Username")
file.WriteLine "DTSTART:" & FormatDateTime(startDateAdd)
file.WriteLine "DTEND:" & FormatDateTime(endDate)
file.WriteLine "LOCATION:MSS"
file.WriteLine "TRANSP:OPAQUE"
file.WriteLine "SEQUENCE:0"
file.WriteLine "UID:" & uniqueID
file.WriteLine "DESCRIPTION:New Hire Start Date."
file.WriteLine "SUMMARY:New Hire Start Date"
file.WriteLine "PRIORITY:5"
file.WriteLine "CLASS:PUBLIC"
file.WriteLine "BEGIN:VALARM"
file.WriteLine "TRIGGER:-PT15M"
file.WriteLine "ACTION:DISPLAY"
file.WriteLine "END:VALARM"
file.WriteLine "END:VEVENT"
file.WriteLine "END:VCALENDAR"