You can thread G10, Micarta, FRN and other man made materials. They can strip easier, they are more prone to cross threading accidentally and if you make a habit of removing the screws a lot it can weaken the grip and bite of the threads over time but if you put the clip on threading idealy with a #50 drill (note I use a #47 or #48 drill for metal and harder materials but the smaller #50 for softer ones) and a 2-56 tap you can put a clip on there and not have to worry about it. Just don't use super glue on the threads, or loctite, don't make a habit of taking the screws in and out, and never overtighten the screws or you can strip out the threads very easily this way also. Follow those rules you can get a long life. I did some Cold Steel FRN folders over 15 years ago for folks that still have them using them with nothing other than the FRN threads holding the clips on. And no, contrary to popular belief by some you can't pull the clips off on these materials or pull out a big chunk of the material. I've tried.
This is not so say its the ideal way because its not. It can work and has. I do it all the time and although its always best to have a metal backing its far less work and far less money if you are paying for it to have it threaded the way I mention above and should they strip later well, then you can always add the metal backing later when you actually need it. You can cheat your way to longer thread life in these man made materials by simply doing a few tricks so to speak. One I've learned from experience is to use short screws that only go in far enough to bite and hold good but not down all the way but just half or slightly less. This leaves fresh unused threads deeper in the G10 or Micarta material for a rainy day if you threaded all the way through the scale which I recommend you do. Should the screws strip later just switch that screw out for a longer screw and you can then grab some of those fresh unused threads deeper down in the hole and still squeeze more life out of your clip mounting.
If you just a metal backing here is a good one. A good way to make some quality backing inserts of metal is to simpy purchase a 1/8" pivot barrel in hardened stainless steel already threaded for 2-56 screws and slice off thin end cuts of that barrel using a Mizzy Cut Off disc or one of the thin cut off discs from the dremmel section of a store local to you. Take those slices on the barrel down to where you can just bend it off the barrel so it snaps off with a twist by finger pressure. What you want is to do this so your end cut has got a little nipple still protruding out of it that should be needle sharp if you do it right and then be sure to insert it on the underside of your scale so the needle part goes in first through the G10 or Micarta scale.
Before you get this far you need to remove the scale after you've marked and drilled your pocket clip holes in the correct positions to lay it flat so you can operate on the underside. Once the scale is off drill some shallow 1/8" holes just deep enough for the inserts you cut to fit down in so they nest down there nice and neat. At this time you'll also need to drill those holes that you threaded through the G10 or whatever material the handle scale is made out of and use a #44 or #43 drill to allow the screw to pass through without biting or restriction. Your insert is going to be your retention now and those threads in the G10 or Micarta scale will just mess you up for trying to insert the end cuts.
The little nipple needle protrusion should go in first and use the screw to pull those end cut slices of threaded barrel into the holes. When they pull in tight the nipple will dig into the G10 or Micarta and then grab and prevent the insert from spinning free on you when you tighten it. It adds a bit of retention also. Once they are down and the clip is tight and you have inserts for a steel backing already threaded for 2-56 you can coat the underside of both or all three if its a three hole clip you own and do this with a thin layer of super glue to prevent those inserts from falling out should you go to take the clip on and off later. Let that set up and stick it back together and you should be good to go. Of course this is not full proof either and there are other ways to do it. You could simply drill the pattern for the hole mount of your clip on a small sheet of scrap titanium or stainless and thread the holes using a solid plate on the underside of the scale just as well but you'd probably have to nest that in place also so the blade didn't hit it when it rotated. Its faster and easier to use something round you can just drill some quick shallow holes. Trust me I've done both.
By the way. Trying to use the 2-56 or 1-70 screws to make your threads in these materials is a good way to twist a head off a screw and leave a threaded stem sticking out the end that you have to grab with a small pair of vice grips to remove if you are lucky enough to have a long enough piece to get vice grips to grab onto that is. Don't do it. At the least it can weaken the screws so they snap off later. It can also strip out the hex or torx heads of the driver needed to turn them. Use the tap.
STR