Hi-
For selecting the green monochrome map in AFNI:
Open an overlay in the AFNI controller. When it has opened, you will see the default colorbar (usually red...yellow...green...cyan...blue). Right-click on this colorbar, and you will see a small, three-line panel open up. Left-click on the bottom line, "Choose colorscale." Now you have a list of colors (probably the same list as in SUMA). For me, 'green_monochrome' is the 21st one in the list (they're not alphabetical).
Also, for any colorbar in the AFNI viewer, you can invert the representation by left-clicking on the colorbar.
--pt