Enigma1 support seems to work fine on my DM600 now!
Only the 'exit' button doesn't seem to work, but that is the button in the web interface labeled as 'lame'.
And the menu button code is the same as for enigma2, the web interface shows dream on the menu button. I've attached a screenshot, so you can see what I mean. The real remotes are exactly the same, I have no idea why they played with this in the web part