a me viene in mente di usare la modalità binaria
aggiustando la dimensione del buffer quando conosco la lunghezza del record
...qualcosa tipo:
codice:
Dim inf As Integer
Dim j As Long
Dim sTmp As String

Dim Buffer() As Byte

ReDim Buffer(1 To 1)

inf = FreeFile
Open "c:\temp\buffer.txt" For Binary As #inf  '123456789012345678

Get #inf, 2, Buffer
sTmp = Chr(Buffer(1))
Debug.Print sTmp

'leggo  4 byte alla volta
ReDim Buffer(1 To 4)

Get #inf, 5, Buffer
sTmp = ""
For j = LBound(Buffer) To UBound(Buffer)
    sTmp = sTmp & Chr(Buffer(j))
Next j
Debug.Print sTmp

Get #inf, 1, Buffer
sTmp = ""
For j = LBound(Buffer) To UBound(Buffer)
    sTmp = sTmp & Chr(Buffer(j))
Next j
Debug.Print sTmp

Close #inf