I don't think that there is an equivalent concept in either WinClient or Linq.
In Classic, about the only use that I found for the Entity[Ordinal] capability was to assign a value to a read-only property (e.g., Employee[0] = 1234). This is a workaround for the problem that Employee.Id = 1234 generates a coimpiler error. Is this the problem that you are trying to solve?