In the video Q&A w/Emil that Mike posted, Emil said he views the instrument as a standard tuning six-string with an extra low B. Which, so far, is how I've approached it.
But the other day I was reading something (maybe the Carcass article in Guitar World? - really don't remember) that made me think...
Has anyone approached it as a down-tuned six string with a higher 7th string? The thing I read talked about this guy tuning down to B, and for whatever reason, it suddenly popped into my head - I could tune down to B with the high E string becoming an added D above the high B.
Anyone doing anything like that?