Basic Rotation / Transform Question

I’m trying to make a ParticleEmitter shoot particles relative to a node other than the rootNode (i.e. flames shooting out of rocket engines). node.setLocalRotation doesn’t change the direction the particles shoot from, but particleEmitter.setInitialVelocity takes a Vector3f and node.getLocalRotation returns a quaternion.

I guess my question is, how do I make a quaternion a vector3f for rotation?