It looks as though the main engine is a rocket.

Vectoring thrust from a rocket is done today, by moving the nozzles, however, the range of motion is limited.

In order to vector thrust for the maneuvering, there should be maneuvering thrusters, as there are on the current space shuttle. Since the vehicle is going to use some sort of rocket fuel, either solid or liquid, for it's main engines, it would make sense to use the same mechanisms for the maneuvering thruster systems.

RE: Academic VC: XCOR announces Lynx spaceplane