VBS has a great function - replace. Next VBS script lets you replace string  in a text file. Replace works with text compare (case insensitive). Use: 
[cscript|wscript] replace.vbs Find Replacewith File

Find … Required. Substring being searched for.
Replacewith … Required. Replacement substring.
File … Source and destination file for the replacement

Dim FileName, Find, ReplaceWith, FileContents, dFileContents
Find         = WScript.Arguments(0)
ReplaceWith  = WScript.Arguments(1)
FileName     = WScript.Arguments(2)

'Read source text file
FileContents = GetFile(FileName)

'replace all string In the source file
dFileContents = replace(FileContents, Find, ReplaceWith, 1, -1, 1)

'Compare source And result
if dFileContents <> FileContents Then
  'write result If different
  WriteFile FileName, dFileContents

  Wscript.Echo "Replace done."
  If Len(ReplaceWith) <> Len(Find) Then 'Can we count n of replacements?
    Wscript.Echo _
    ( (Len(dFileContents) - Len(FileContents)) / (Len(ReplaceWith)-Len(Find)) ) & _
    " replacements."
  End If
  Wscript.Echo "Searched string Not In the source file"
End If

'Read text file
function GetFile(FileName)
  If FileName<>"" Then
    Dim FS, FileStream
    Set FS = CreateObject("Scripting.FileSystemObject")
      on error resume Next
      Set FileStream = FS.OpenTextFile(FileName)
      GetFile = FileStream.ReadAll
  End If
End Function

'Write string As a text file.
function WriteFile(FileName, Contents)
  Dim OutStream, FS

  on error resume Next
  Set FS = CreateObject("Scripting.FileSystemObject")
    Set OutStream = FS.OpenTextFile(FileName, 2, True)
    OutStream.Write Contents
End Function