You cannot make the change fluidly though. The action above just sets the transparency and colors to the set amount. So there's no nicely looking change from solid-looking model into half-transparent one... to do that requires a trigger that fires periodically (e.g. every 0.03 second) and change the values little every time (e.g. by 3%). That will make the change fluid.
The three fields before the transparency are for setting unit's RGB (Red/Green/Blue) values. When all are at 100%, the unit has normal coloring.
Since you want to make it more green, set the values R and B into ~80% while leaving the G value at 100%. You can play with the values as you want to find the coloring you like.