All you need is thread (preferably the bead's or the cloth's color), beads, and a needle small enough (special beading needles work fine, but regular ones can work sometimes).
I use size 11 seed beads, they're about the same size as what a perfect french knot would be, and look great.
Steps: Thread the needle, and push through the cloth where you want the bead to be. Next, add the bead to the thread, so that it is directly where it would be in place of a french knot. Push the needle back through either the place you came up or slightly to the side of where you came up (Important: don't go back through the bead!) to secure it. You can then add more beads or simply tie off like you would normally.