Go to tools->Customize screen tosee if the icon already exists. If not make a mapkey that does the function you want. Then you can either use the hotkey to perform the action or create an icon for your mapkey. If you want to do the latter go to tools->customize screen again and go down the the mapkeys area, choose the mapkey you just made and place it on your toolbar, you can edit the icon image to whatever you want as well.