How can I change the order of records in a non-indexed table so as to move one record before another.

Here's the scenario: When entering step-by-step instructions on a Shop Order (to tell employees the order in which a job should be done), sometimes, you want to go back and add a new step between two existing steps, or after a certain step, or before a certain step. The records are collected in a grid, where a command button on the form does an append, then passes focus to the new record in the grid. How can I allow for re-ordering, without having a field in the table that stores the sequence number?

I need a mover or something.