Use a VBA macro...
vb code:
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Target = Target + 1
End Sub
Obviously just add a few conditions if Target is column A for example and if Target <> ""
EDIT: A bit more in depth:
vb code:
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Target <> "" And ActiveCell.Column = 1 And ActiveCell.Row < 50 Then
Target = Target + 1
End If
End Sub
ActiveCell.Column uses numbers to represent columns instead of letters so A = 1, B = 2 etc.