Hi,
That sort of camera will not work.
The USB output of the Video is not the sort that iChat or Messages can use. (And neither can Photo Booth).
You will need a computer that has USB 2.0 ports (I am not sure an iBook of that age is going to Have them (my G4 Tower did not until I added an PCI card with them on).
You are going to need a USB 2.0 camera that is what they call USB Video Class Compatible (UVC for short)
At the time Vista had just come out and PCs were adding Video chat abilities via "Vista Compatible" cameras (which just meant they were UVC compliant).
Nowadays all USB cameras tend to be UVC and not many of the published details even mention it any more.
A Firewire Camera (very few about nowadays) has to be the speed your ports are (if your iBook has them) My Tangerine G3 one does not it only has USB 1.1 ports.
The Original iSight (which was External) was Firewire 400.
Be careful with second hand ones (try to check they work before you buy).
If the Canon Powershot G4 has A/V out put in addition to the USB port it has you might be able to find A/V to Firewire converters (often they do various combos such straight through Firewire (some older Sony Video Cameras had a D shaped Firewire port called iLink) as well as A/V (RCA cables) and S-Video (And similar options for Output) - they were not only aimed at linking computers to Cameras.
I had a Dazzle item from Pinnical (No longer made as USB 2.0 was faster than Firewire 400).
(one of these types of devices - Google Search Images.)
This specific one has three pics showing back and front with the Firewire port http://www.grassvalley.com/products/advc110
9:27 p.m. Monday; August 17, 2015
iMac 2.5Ghz i5 2011 (Mavericks 10.9)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad
