Use a serrated knife to trim point of each cone to create a small opening; set aside. If necessary, use the serrated knife to trim top of each cupcake to create a flat surface. Place a dab of frosting on top of each cupcake, and spread to cover. Dip the top of each cupcake into coconut to cover completely.
Mix together remaining frosting with green gel paste until desired green shade is reached. Transfer green frosting to a large pastry bag fitted with a small star tip. Working with one cone at a time, pipe a bead of frosting around open end of cone and position open-end down onto a cupcake to resemble a "tree." Repeat process with remaining cupcakes and cones.
Pipe remaining frosting decoratively all over trees until cones are completely covered. Trees can be refrigerated, uncovered, for up to 6 hours. Before serving, insert a cupcake topper into the opening of each cupcake cone, if desired.