Grapple Platform Action

Hi I'm looking at using a grapple style action with swinging. Can anyone talk me through how I can make it work. I understand alot of it, but this is the one thing I cant seem to understand how I can go about this.

Any help is greatly appreciated :)

Thanks! <img src="smileys/smiley20.gif" border="0" align="middle" />

It's a lot easier to explain with an example:

Demo

Capx (with annotations)

I hope it helps.

Thank you very much! This is great to work from! Your the best!