I think that you need explicit solver and CCX is implicit and explicit solver. See *DYNAMIC input deck. In explicit analysis no iteration is required as the nodal accelerations are solved directly.
I would think any dynamic analysis could be used as inertia relief, even if it's inefficient on computer resources. Either use a single time step or have damping so the final state is a rigid body acceleration with deformation from the loads.
Note that inertia relief isn't needed when all the forces are balanced. In that case, put individual node constraints to prevent rigid body displacement and rotation about all 3 axes. See attachment.
Comments
In explicit analysis no iteration is required as the nodal accelerations are solved directly.