Artillery Bombardments - Defined Hexes + Trenches

[Pazam]

I noticed in a number of battles that come with the game that there are pre-defined hexes for artillery so that the time from setting the bombardment until shelling begins is minimal. For example, in one scenario if you select the pre-programmed hex artillery arrives in 0.5 turns while any other hex is around 2.2 turns.

How do you program this in the editor?

Also, how do you add trenches to a map in the editor?