Just had to say that I finally got my asymmetric spinnaker flying last Friday :) I bought it last year, at the same time that I replaced my main and jib, but it's taken a few iterations of tweaking the rig, and well as suitable conditions to try it out. But at last it worked!
I had to mount a halyard block at the very top of the mast, and I bought some lightweight "spinnaker plait" for the sheets, which run through blocks attached to the aft lifeline fixings. I ran the tack downhaul to the cockpit to provide full control, and the Chute Scoop dowsing sock is also controlled from the cockpit. So apart from actually hoisting the chute in its sock, everything can be done from the cockpit - in theory :)
Here's some pics
To set it properly I found I had to adjust both the sheet and the downhaul at the same time, sometimes one in each hand. I secured the downhaul in the jib-sheet cleats. I think I might double-up the downhaul and run one each side, so I can always have a live one on the same side as the live sheet, and leave the lazy one slack.
I keep the downhaul routed through the pulpit by leaving the mast securing bolt in place, running through a piece of ali. tubing so it doesn't chafe the rope.
I ran the sheets right round in front of everything, so the spinnaker could be easily gybed. The only problem is that if you let the lazy one go too slack it can fall into the water and go right under the hull :( The alternative is to run the sheets aft of the tack, so you then switch the spinnaker through the slot it creates between itself and the furled jib. I've heard this can be done, but it seems to me there's more risk of catching and damaging it. I might give it a try though.
If anyone else has used one of these, I'd be interested in any tips!
Cheers.