The scales are screwed on with what looks like a small torx head screw. Some of the CRKT knives that have removable and reversable clips on the sheath have what looks like a hex key for the clip. My boxes are buried presently so I can't tell if they would fit the handle on the knife.
If you are wanting to make a thinner, non-slip handle there is a plastic coating material that you dip tool handles into and if forms a grip like you see on pliers and such. Heat shrink tubing could be used too, but I don't know how slippering it would be. Cord wrapping could be a solution too. There are some links/instructions somehwere on bladeforums IIRC. A search of the forum might reveal some info. Cordwise, I like good old fashioned parachute, aka 550 cord. Given my Army past I might be a little predjudiced there. There are also some brighter colored cords out there that work good.
Also, in the accessories area of the forum for sale section there are a few fellas who offer some really sharp and useful corded products such as monkey fists and other knot related lanyards and thongs. Here's one link to the area:
http://www.bladeforums.com/forums/showthread.php?t=394604
Another cheap tinkering knife in the bigger size is that Gerber Profile right beside the F4. At about the same price at WalMart the scales are also Torx screwed on and it is looks like it would be a good project either for doing a wrapped handle on or maybe a restocking with something interesting. It is 440C with a nitride coating, full tang, well balanced, and it sharpened up nicely. At $19.95 + tax it's cheap thrills. I'm planning on picking up another one or two to put through some hard testing just to see how much knife is there. Generally, Gerber doesn't get much respect these days and I generally don't go for Gerber these days either, but I like this one so far.
So for about $40 you can have two full tanged knives that seem to work just fine. They aren't braggin' blades as far as maker or custom look, or even handle material. But for giving a good deal for the dollars they are both pretty good. I've used the spine on both to make sparks from my Boy Scout firesteel so they could be a fire making kit and still have an edge.
Sorry, got to rambling.