Mouse Over Object

Im building a game and which is about 50% complete but have one little easy problem I need the script for a crosshair I already made the mouse hide and started the drag true but need script for when I mouse over a enemy the crosshair turns red then when I take it off it goes back to blue. I already made two frames in the crosshair the normal state and the over state. Oh also I dont want the enemy to be a button with a invisble I want him to be a movie clip. So what do I do? I thought about on rollover and rollout but cant think of any other script to go with it.
Please help