iMac G5 (iSight) and iMac (Early 2006) computers, while similar in form to previous iMac G5 models, are not compatible with the iMac G5 VESA Mount Adapter Kit (part number M9755G/A).
The 24-inch model of the iMac (Late 2006) is compatible with a VESA mount adapter. Use the iMac 24-inch VESA Mount Adapter (MA473G/A). You can view the installation guide here.
Apple will not be offering this kit for installation on iMac G5 (iSight) or iMac (Early 2006) computers.