I use bongos2, it allows me, after much setup, to one button and simulcast a keystroke for every ability I use. So for me, I set all my toons with earthbind totem, and I bound that ability to alt x. All 5 cast it at the same time. I don't know of another way to do it, though there probably is. Bongos freaked me out when I first loaded it, but take the time to learn it. Helpful to know first, that you organize where on your screen you want your action bars, themselves. Then lock the bars and add abilities. Then use the bindings feature, follow the tooltip and done.