Sounds like you want the ADODB.Stream object. I use the following code to receive a binary file upload from the client and write it to a file on the server:
Dim adoStream, stream
Set adoStream = Server.CreateObject("ADODB.Stream")
adoStream.Type = adTypeBinary
stream = mpRequestFiles(fld, 1)
adoStream.SaveToFile Server.MapPath("/uploads/" & fileName), adSaveCreateOverWrite
Set adoStream = Nothing
Perhaps you can get this code to work for you.