You can manually set rotation values using Model.Direction.<X/Y/Z>. Not sure, but I think they are local transforms ( relative to the model, not the world ).
The help file says that Model.Direction is a 3D Vector - the help file is wrong here. Whereas a 3D vector is a set of position values, Model.Direction is a set of 3 rotation values ( X, Y, Z ).
Using Model.Direction is not as simple as it should be. The angles are not measured in degrees ( or radians?? ). To set a rotation value, you need to multiply a degrees value by PiOver180:
Var PiOver180 as decimal = ( Math.Pi / 180 ) // This should be a global variable, so you only have to make the division once
Model.Direction.X = <degrees> * PiOver180
Not sure how to get the value in degrees though... Maybe Model.Direction.X / PiOver180?
Hope this helps.