Implementing CV1 support into a Lever program follows the instructions on the Oculus SDK. Similarly to OpenGL and SDL2 headers of Lever, the headers of LibOVR drop the ovr_ -namespace prefix. You may still need advice on how C-FFI works on Lever. So far there's an example of how to retrieve HMD tracking state at samples/oculus_rift.lc of the github repository.
Even if the support is there now, it still takes a while before you see the first VR demo written in Lever. The language needs vectors and matrices before that happens.