When a unit has stealth, clicking on a provence sneaks them there, control clicking on a province moves them there. so if you want them to attack a province, you need to hold control, then click on the province to attack.
Its still a bit of an annoying system, and you often forget and only attack with half your army or something.
Edit: oh and here is a graphics boost, its still in its early stages though
http://z7.invisionfree.com/Dom3mods/...p?showtopic=80