So there is no way ... because dragon miners need the difficulty to be handled be the pool .
I try the dragon miner on Eligius and does not give normal speed
I have 3 (4 blade) 1TH/s Dragon miners and I've selected 256 for mining difficulty via web interface and all 3 have been mining just over 1TH/s for 3 weeks
edit. I've just noticed in the stats page that the difficulty is actually set to 511.99, so not sure what the setting via the web interface does.