See here (eth-proxy relaying method):
https://github.com/Atrides/eth-proxy/blob/d993fc8db84dc09f25b72a34ce69b6977c88ac64/mining_libs/getwork_listener.py#L58-L62
Edit:
Also see (ethminer creating eth_submitHashrate commands):
https://github.com/ethereum/libethereum/blob/8b389757cfc2757965671fa8e080b32aaf65771b/ethminer/MinerAux.h#L536
https://github.com/ethereum/libethereum/blob/6d65d5d1412013381324826ea583e8b3fa9f5f3c/ethminer/FarmClient.h#L37-L47
Yes I found "eth_submitHashrate" but I'd like to check some miner that sends this command to see how it works. There is no any documentation about it but it seems it has two params: first is the hashrate, second is filled by random and it's strange, it must be worker name so pool can know who reports the hashrate.