Up to this point, there is absolutely no reason ken should not be in the final 3 (If there was an episode on thanksgiving I didnt see it, Im up to where Randy got owned)
Ken and Crystal know Sugar has the idol, so they have to convince sugar that they will be the final 3, and if she turns on either of them (which she is likely to do, since shes angry at ken for making her betray Ace) then the remaining member will rat her out about the idol. Convince her that she can use it on the final vote if she sticks with them. Tell her at the final vote, they will vote off suzie and Sugar can be completely safe by using the idol. Also tell Sugar that they will tell Suzie that Suzie is gonna be in the final three.
Meanwhile convince suzie that she is gonna be in the final 3 with them since she basically saved them, and they owe her. Also tell Suzie that they are telling Sugar Sugar will be in the final 3 (suzie doesnt know about the idol) and that they will vote suzie off. Tell her if Sugar approaches her stating that they will vote off suzie at the end, to act surprised, and outraged, and pretend to be on her side.
If they do this, no matter how many individual immunities are won, assuming suzie doesnt win an individual immunity for the final vote ( .... ), ken should get to the end. Suzie and sugar's only choice is to stay on the winning team. The risk of turning on the ken/crystal pact is way too great for either to do, AND even if 1 turns, the other will think that its all part of the plan.