How to implement Tagetless IK?

What’s the best way of implementing a Target-less IK on top of a FK/IK switch. It used to work on 2.4x but ain’t work for me on 2.56 r35853. Am I missing something? If not, is there any other alternative or recommendation?

I just add an IK constraint to the desired bone, set chain length and everything but leave the target field blank. Works fine.

I applied the same method you have mentioned, but sometimes the movement of the bone-chain gets ‘haywired’, don’t know why! Thanks though for the quick reply.