I want user to enter into the layout mode via a script button so they can add fields to a list that is in 'view as table' mode.

Can anyone tell me where to find this.

There is not a script as you say. But if you want the users to enter a new field or fields you can make a script and use "Open define database" script step.

Trust me, you don't want just anybody modifying layouts.

If they can't enter layout mode without a script, they probably can't add fields to a layout either.