Zoom Extents, and use the AutoCAD MSLIDE command to shoot a slide of the same name. You will then also need to use the Land F/X Make Slide Libraryfunction to recreate the slide library for the folder LandFX\Blocks\Graphics\Callouts.
The Irrigation Valve Callout blocks are located in the Callouts folder under LandFX/Blocks/Graphics. The callouts are named VALVECO, then a number for the callout type, a dash and number for the valve size, and then a dash and an L (for left) or an R (for right).