I haven't tried this out yet, in theory though it should work, for a homing missile, you could insert a sprite with bullet and 8 direction behavior and have it rotate towards the moving object you want it to target.
con 1: on mouse clicked
con 2: 'crosshair' overlapping enemy >
action1: spawn 'homing missile' at 'launcher' (X,Y,)0
action 2: rotate towards enemy
let us know how you do ;)