Is this a knock-down knife? The reason I ask is that most fixed blade knives have pinned scales -- they're not removable and, in most cases, you wouldn't want them to be.
Nevertheless, you're not going to find the kind of screws you're looking for in those small sizes. The best you can do is buy a couple of folding knife pivot pins and the corresponding screws. The 1/8" pivots are threaded for 2-56 screws. The 3/16" pivots for 4-40. Max length is 1/2" on most of these, but if your screws are long enough, you might be able to make them work.
I buy a lot of my hardware from IBS International. Give R. B. Johnson a call at (320) 558-6128. He's got virtually every kind of screw a knifemaker could ever want, plus the pivot pins. He's in Minnesota. I don't think he has a web site.
-Frank