如何实现以16进制方式打开指定的文件并查找替换16进制数值？

Function ReadBinary(FileName)
        Const adTypeBinary = 1
        Dim stream, xmldom, node
        Set xmldom = CreateObject("Microsoft.XMLDOM")
        Set node = xmldom.CreateElement("binary")
        node.DataType = "bin.hex"
        Set stream = CreateObject("ADODB.Stream")
        stream.Type = adTypeBinary
        stream.Open
        stream.LoadFromFile FileName
        node.NodeTypedValue = stream.Read
        stream.Close
        Set stream = Nothing
        ReadBinary = node.Text
        Set node = Nothing
        Set xmldom = Nothing
End Function

Sub WriteBinary(FileName, Buf)
        Const adTypeBinary = 1
        Const adSaveCreateOverWrite = 2
        Dim stream, xmldom, node
        Set xmldom = CreateObject("Microsoft.XMLDOM")
        Set node = xmldom.CreateElement("binary")
        node.DataType = "bin.hex"
        node.Text = Buf
        Set stream = CreateObject("ADODB.Stream")
        stream.Type = adTypeBinary
        stream.Open
        stream.write node.NodeTypedValue
        stream.SaveToFile FileName, adSaveCreateOverWrite
        stream.Close
        Set stream = Nothing
        Set node = Nothing
        Set xmldom = Nothing
End Sub

Private Sub Form_Load()
Dim str As String, i As Long, j As String, k As String

str = UCase(ReadBinary("1.fas"))  '获取指定二进制文件的十六进制代码，代码形式：4D5A90000300
'MsgBox str

For i = 1 To Len(str) Step 2
    j = Mid(str, i, 2)
    k = k + " " + j + " "
Next
k = Right(k, Len(k) - 1)
k = Left(k, Len(k) - 1)
'MsgBox k  '获取格式化之后的十六进制代码，代码形式：4D 5A 90 00 03 00

'替换字符串(有多少替换写多少行）：
k = Replace(k, "1E 6F 11 55 55", "00 6D 00 00 00")  '1E 6F 11 55 55 替换为  00 6D 00 00 00
k = Replace(k, "1E E3 11 55 55", "00 E1 00 00 00")  '1E E3 11 55 55 替换为  00 E1 00 00 00

k = Replace(k, " ", "")   '写回二进制前，记得要把格式化之后的十六进制代码还原为格式化之前状态才能写入。
WriteBinary "New_1.fas", k   '写回二进制文件,文件名若为同名则写入相同文件
End Sub