So basically you want the missile to point in the direction it's travelling. Align to vector on the z-axis, based on the new x,y,z velocity should work - as you're doing. What kind of results do you get? Sometimes the align to vector doesn't always do what you expect so until someone more familiar with the command comes along...
You create a global pivot, parent it to the missile, position it at dx,dy,dz then use point entity. This will work.
Stevie
You create a global pivot, parent it to the missile, position it at dx,dy,dz then use point entity. This will work.
Stevie