I've made a cable and successfully tested the mixer. I ended up opening the mixer to trace out the pin connections, the wiring diagram and the names of the connector types I used is attached. I was able to get both connectors for a reasonable price on ebay, although I ended up buying a few similar ones just in case. For cable I just used 7 core 'trailer cable' and doubled the wires on the +/-17V pins so there's lots of extra copper for main rails and ground. It's low impedance so doesn't need shielding.
I couldn't see any specs for current, but as a rough rule of thumb for mixers I'll usually allow 10mA per channel for phantom and 100mA per rail per channel for the main +/- then add some headroom. So for a 24 channel desk this would be at least 240mA at 48V and 2.4A per rail, I'd probably double them to 500mA and 5A just to be safe. That's being very generous, but as long as they're regulated supplies it won't be a problem. You don't know how much the master sections, metering etc is drawing hence being generous. The Toft is a chip based desk so won't be too bad, if it was discrete or had all channels with backlit VUs I'd allow a bit more.