Well, I've never wrapped a handle before, but I consider myself pretty handy with rope. So, I'll give you some ideas.
- I believe some people just glue the cord on. I hear gorilla glue works.
http://www.throwzini.com/cord_wrapping.html
- This site shows a method to do a double layer wrap. You could use either one by itself also, but the first one would need to be ended. One way of doing this would be to loosen, tuck, tighten such that the last end is tucked under just like the end you started with. This may prove difficult to get tight enough. if you had a hole somewhere you could tie it off too (maybe using a small stopper knot), that would work also or perhaps a slide grip hitch could also work.
For the second method, they use this as the top wrap, you should be able to do this one independently, by itself. Also, you wouldn't necessarily need to start in a hole like they did. My guess is that if the wrap is done tight enough it shouldn't slip.
Also, if I were wrapping a knife, I'd put it in a clamp. That way I could have 2 hands free to make the wrapping really tight.
let me know if you want further explanation.
****Edit*****
I just found a couple more sites
http://www.m4040.com/Knifemaking/cordwrap.htm
http://trainingblades.com/index.php?option=com_content&task=view&id=15&Itemid=28
The first one uses the first method I mentioned and the second gets a pretty cool effect by going down the handle with both ends and making one twist per side.