Ah - the first report must be identical to the 6kro report, additional descriptors may support more exciting HID reports, but they will not be available until an OS has booted and brought up a HID parser. :]
Take a look at the way it is done in some of the OSS firmwares, hasu's TMK, haata's kiibohd, etc... and you may also have some fun reading the HID and HUT USB specs too at USB.org, though they are dry, wordy and ambiguous. :/
just woke up, need coffee
dfj