Kevin, I just make sure the two handle scales are flat so they contact the blade evenly and epoxy them in place. If the knife is pre-drilled for rivets you will need to decide how thick you want the handle to be and recess the rivet holes to the proper depth before you glue it all together. Then just stand at a bench grinder and grind away what don't look good to you. I prefer to use brazing rod for pins instead of rivets, just think the small brass pins look better. It's important to use epoxy under any handle to keep the tang from rusting out.
Steve
Steve