Adding a network printer (Canon IP4000R)

Our household has a network with a Windows PC (XP) and a Mac (OSX 10.5.4). Both are connected to a router which has wired ports in addition to wireless (the iMac is wirelessly connected while everything else is wired).
A Canon IP4000R network printer is connected to the router with an ethernet cable.

The printer works fine when printing from the PC, but I'm having trouble adding it to the Mac.

I've downloaded all the software and manuals I could find here (at Canon's website), but the manuals and software just leave me confused. It seems I need to connect the printer to the Mac via USB in addition to the router (using an ethernet cable) which seems pretty strange, not to mention impractical (the printer is in another room).
What's the proper procedure for this?

 

I solved it!
Yes, I did attach it via USB in addition to ethernet, but I spent a long time trying out all sorts of things. Don't ask me how/what I did in order to get it working, but at least I now have both a USB and network printing option for that printer and I'm not going to mess around with its settings again