Since you have to build the mount anyway I would forget about trying to recreate the buttonhook and just use three or four pieces of galvanized electrical conduit or aluminum tubing to make a three or four point support, similar to this:
The advantage to doing it this way is it will be a much more stable mount. The disadvantage is you will have to calculate the length of the rods and more than likely you will get it wrong at first, so I would make them maybe a foot or so longer than you think they should be to start and them measure how far the LNB is to the dish compared to what it should be (this also give you the opportunity to make corrections if the edge of the scaler ring isn't at the same distance from the edge of the dish in all directions. This dish may have already had holes provided for this type of mount but yours probably doesn't, so rather than attaching the rods to the face of the dish I would bring them out to the edge and bend them downward over the edge of the rim so your bolts go sideways through the rim. You will probably have to buy 10 foot sections of conduit anyway so might as well use the extra length to go all the way to the edge. And once you get the LNB pretty close to where to where it should be in terms of distance from the base of the dish, you could make the flattened part that goes over the edge of the dish a couple inches long and make an elongated slot that allows you to slide the rods up and down in order to make fine adjustments, although if you do that I'd use the largest washer you can find (that will fit your bolt) between the bolt head and the flattened part of the rod to keep it from bending outwards. That is the only disadvantage to bending the tab over the edge; if you don't use a thick washer that nearly covers the flattened part it could bow outwards a little over time. Then again, if your aluminum dish doesn't have any rim to speak of, you may have to attach the rods to the face of the dish near the edge, if you want to go this route.
But if you really want to use a buttonhook, this is the best picture I could find:
That one appears to have some kind of clamp mechanism that clamps onto the body of the LNB but on most of the ones I've seen, the flat piece bolts directly to the scaler (sometimes it has a U-shaped slot that the scaler slides into, other times it's just a flat piece that only attaches to the scaler with two bolts on one edge!). On some the center support is two pieces, a straight part that comes out of the center of the dish, and then a smaller rod that is the bent part that slides inside the larger tube, giving a way to adjust the distance from the center of the dish (a hole is made in the outer rod, then a nut welded over the hole and then a bolt in the nut is used to hold the inner pipe in place when it's at the correct length and position). The problem with this is you will have a heck of a time getting the flat piece facing the center of the dish so that when you attach your scaler it is exactly facing the dish. If you use some kind of clamping mechanism that clamps the body of the LNB you may have a little more ability to nudge the scaler and LNB toward the center of the dish but then you may not be able to use a PLL LNB with the cooling fins, depending on the thickness of the clamp.
If it were me I'd go with the first approach. If I get a dish that already has a buttonhook mount I will try using it to see if it will get an adequate signal, because I'm too lazy to rebuild something if I don't have to and I was never any good in working with metal anyway, but if I were going to attempt to build a support from scratch I would never try to make a buttonhook support. But that's just me; it's your choice. Hope these help.
By the way the photos were found using Google Image Search but are both from posts already on this site, so thanks to whoever originally posted them.