Well I don't know about useless. They are a generic part though, so, some fabrication required. For my install with a 1/2" offset, or the stock spring location the easiest way is probably a bracket similar to what I made. Unfortunately the slider needs to be far enough forward that you just can't bolt/weld them to the frame support there.
Now, on a car with a 3" spring relocation you could just bolt or weld them right to the bottom of the frame rail. So, that would be pretty easy. I know younggun2.0 recessed his into the rail to lower his car further, but that's not necessary for most applications. Even just installing the slider in place of the shackle lowers the car slightly, it was around 3/8" or so on my car.
