Hi,
If you want to dive a double hose with modern gear, then you generally use a backplate and wing (called a BPW for short) with a double hose specific plate on it that VDH sells here:
http://vintagedoublehose.com/store/#!/V ... ry=1874499
You build it like any BPW you would find out in the world, then nestle the double hose cans in the crook that is formed into the plate. I'm simplifying that, but half of the fun of this is learning. The best way to do this is to buy what you need and to spend some time in a pool or confined open water environment farting around with everything. Really, other than the plate and the positioning of the regulator, from a gear perspective that about does it. The skills are a little different too, but again that is half the fun.
If you are unfamiliar with a BPW, I suggest your exercise your Google-fu. There are also threads here about such things
The impossible missions are the only ones which succeed. -JYC