Has anyone used one of these Zillion housings:
http://www11.ocn.ne.jp/~zillion/index.html
I did a google translation of the 1DsMKII page and it was very informative. http://www11.ocn.ne.jp/~zillion/EOS1DMark2/index.html

The housings take Inon ports and strobes. The first picture in the third row shows the optical cable sync location. I'm not sure how it works, but it looks like there MAY be an optical converter inside the housing. "Strobo connector 2 standard equipment. When optical cable M of the INON make is used, the external automatic Strobo enabled"
With the D70 housing, there is room for the flash to pop up and there are two sockets on top for mounting the Inon optical cables.

Anyhow, just thought I'd share.
Cheers
James