あるいは、↓ですかね？　↑も↓も「Open "C:\hogehoge.bin" For Binary As #lngFN」の業でパス名が無効です、というエラーがでます。

Sub test()
Dim btByte() As Byte
Dim lngFN As Long

ReDim btByte(5) As Byte

btByte(0) = &H4D
btByte(1) = &H54
btByte(2) = &H68
btByte(3) = &H54
btByte(4) = &H68
btByte(5) = &H64

lngFN = btByte
Open "C:\hogehoge.bin" For Binary As #lngFN
Put #lngFN, , btByte
Close #lngFN


End Sub