The initial voxel cone tracing stuff had realtime generation of sparse voxel octrees as a necessity, take a look at that stuff for hopefully much faster octree generation: https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&es_th=1&ie=UTF-8#q=sparse%20voxel%20octree
Sparse octrees are close to suiting light probe placement, thought not perfect. Some hacks would probably get you there, or hopefully just give you an idea for speeding up AMD's technique. You could also LOD out lightprobes to the bigger voxel sizes as your player gets farther away, a kind of cascaded detail for light probes. Probably have to be careful how you blend in new, smaller voxel/higher detail probes though to avoid light popping.