You could use the wrap that Ranger Rick uses for a knife handle:

The Ranger Digest

Click on "Paracord Knife" on the left hand side. Basically, you make a loop of cord (2nd picture from left), and wrap the remaining cord around the PSK until only a small piece of the loop is visible. Then, feed the end of the cord through the loop, and pull it tight from the top. Trim off the excess.