How do you achieve the color sage green; or which americolor or wilton icing color would I use?

Wilton Juniper Green works well. I used it on the pea pod baby shower cake I made recently and the square wedding cake (check my photos).

Wilton Moss Green makes a sage-ish green as well.

I've heard Americolor Avocado works, but I haven't tried it myself.

I used the Americolor Avocado for these cakes:

http://www.cakecentral.com/modules.php?name=gallery&file=displayimage&pid=378143


http://www.cakecentral.com/modules.php?name=gallery&file=displayimage&pid=96473

It's a little brighter than sage I think.

I also use Americolor Avacado to achieve a beautiful sage green!

I use Wilton's juniper green.