I have the following script which locates all access files on a machine:
strComputer = \".\"
Set objWMIService = GetObject(\"winmgmts:\\\\\" & strComput
This is what you are looking for. In this part: ("C:\test.txt" ,8 , True), the first parameter is the path to the file. The second parameter is the iomode option. There are three options for the second parameter, 1 means for reading, 2 means for writing, and 8 means for appending. The third parameter is a boolean, true means a new file can be created if it doesn't exist. False means a new file cannot be created.
Dim FSO
Set FSO = CreateObject("Scripting.FileSystemObject")
Set OutPutFile = FSO.OpenTextFile("C:\test.txt" ,8 , True)
OutPutFile.WriteLine("Writing text to a file")
Set FSO= Nothing