Air box off. Feed the idle cable through, following the path of the old one if it's there. Recommend a pair of long nosed pliers of forceps (preferably slightly curved).
If you look at the attached pic towards the rhs the end goes in the hole circled in yellow and feeds around the slot parallel to the red arrow. It anchors in the little fork on the right. If you turn the little widget all the way to the right (clockwise) it makes it slightly easier to get the end of the cable into place.
https://drive.google.com/file/d/0B_Pqm7oEcUniNmN2NFJwZUhnaGs/edit?usp=sharing
There will probably be a great deal of swearing during the process.
If you look at the attached pic towards the rhs the end goes in the hole circled in yellow and feeds around the slot parallel to the red arrow. It anchors in the little fork on the right. If you turn the little widget all the way to the right (clockwise) it makes it slightly easier to get the end of the cable into place.
https://drive.google.com/file/d/0B_Pqm7oEcUniNmN2NFJwZUhnaGs/edit?usp=sharing
There will probably be a great deal of swearing during the process.