Sub AddUserEditRange()
Dim ws As Worksheet, aer As AllowEditRange
Set ws = ThisWorkbook.Sheets("Protection")
ws.Unprotect "Excel2003"
Set aer = ws.Protection.AllowEditRanges.Add("User Range", ws.Range("A1:D4"))
aer.Users.Add "Power Users", True
ws.Protect "Excel2003"
End Sub