Best I have is this one. It's recent. so you may have seen it already.
There's no wind in the picture, so everything has collapsed down, but that way, all parts fit into the picture.
And then there's picture by Phill Root, a former champion DS sailor.
I simply have a hook underneath the coaming where I hook the knot that connects the two ends of the traveler. (The knot is a sheet bend, where I doubled up one of the lines before tying it, so that a loop sticks out instead of a free end - just try it, and it will become apparent). That loop is what goes around the hook. (The line is grossly oversized, but it's from a time I rigged a temporary one to figure out what I wanted).
Phil tied/spliced together both ends and then has one tail go into a cleat. I can cast loose the traveler altogether or center it. He can fine-tune it. Otherwise the setups are the same.
There's a variation that dispenses with the block and separate line for the traveler. In that, the mainsheet gets run from the boom end block to one of the transom blocks, across to the other, and back up and tied to the end of the boom (or more likely to a becket on the block at the end of the boom). It's the least adjustable of all these variants, but also the simplest. The mainsheet will form a big triangle.