Just turn up at editorial board meetings for the journal of your choice. Most editors are somewhat vague about who their colleagues are, and after a couple of meetings they will simply presume there was an accidental omission of your name on the list on the journal. Do not worry that you will not be able to find where these board meetings are held; every member of a editorial board will always let it be known casually in conversation, that they can not join your party for dinner because they have a editorial board meeting. That is when you can say, “yes me too, what a drag!”
Edit a special issue of the journal of your choice; the best way of being allowed to do this is to organise a workshop.
Be a PhD student of an important editor.
Start your own journal and edit it.
Wait for an entire editorial board to resign on a matter of principle, and then offer your services to fill the gap. No-one will remember the mechanism once you are a big shot.
Just keep asking if you can become an editor; you will be successful just to be shut up.
If you are editing a book, there is no need to give any instructions to the authors about the formatting before submission (this might put them off). For example, you do not want to put authors off by telling them what margins to use. It is better to allow them to type their paper in latex, and if it does not meet (for example) the margin requirement, get some illegal immigrant to retype it in Word and send to the authors, who will be delighted to proof read the paper again.
Selflessly spend much of your time doing careful, thoughtful and timely reviews of papers for the journal of your choice. Eventually you will be asked to become an editor.