Here is a good overview of the mod. I just used a 36" x 1 1/2" (or maybe 2") piece and it required no cutting. It is very simple. The furniture bolts are used because they have low profile heads and nuts. I happened to have these laying around AND they happened to be black. Happy coincidence. Just get it square, slip it in, test movement, clamp the bejeesus out of it, and drill away. I am certain you can use a hand drill, just be patient. If you did, you might not even have to remove the gantry.
There are threads where this very simple mod is vastly overcomplicated… ignore them. Unless you are an engineer, in which case, enjoy them.