Enter build mode by typing "build" in the console command while testing your game. (~ to bring up console)

T/G to scroll through decorations

Q/E to change grid size.

Arrow keys to nagivate Rotation controls (for 3d models) aswell as Scale options for Billboard sprites.

Left mouse click to place objects.

NOTE: to save your build mode placements, enter open the console and type "build save". hit enter.

Your placements will be saved in map.script file named [yourmapname]Ent.script

simply copy the lines in this script to your map.script and they will be placed.

NOTE: everytime you "build save" a new mapEnt.script file is created and will overwrite the last.

They can always be removed later.