Hi PAHU,
Here are three of the fundamental issues you are missing.
1 - We're talking about a different product. Do you own a MF4570dn? If your answer is "no" it appears you are giving holier-than-thou advice about other users incompetance about a product you have not even tried!
2 - You are not acknowledging the odd reality about MF Toolbox not being an application. Early on in this thread you stated this:
The ScanGear installer creates a folder in Applications called Canon MF Utilities. Inside of this folder will be the MF ScanGear utility.
But Captain Rocky points out one of the oddities of this software:
I found the Canon MF Utilities folder and the MF toolbox. (why doesn't spotlight find MF Toolbox as an application??)
Here's the reason Spotlight might not find MF Toolbox as an application. It's not an application! See the below screenshot. It looks to me like MF Toolbox isn't even an actual piece of software -- it's just an alias that points to a utility elsewhere on the hard drive.

- You are misunderstanding the issue with the MF Toolbox. The issue is not that it won't "find" the piece of hardware. The issue is that the software is buggy & prone to instant crashes and complete unresponsiveness. Here are your comments.
So, I'll start the assistance by asking if you have managed to get the device to scan using MF Toolbox? Your image shows you using Image Capture and that MF Toolbox is failing. But I wonder if the same occurs when scanning with MF Toolbox. You can open it via Applications > Canon MF Utilities. With it open, click the Save button and with the settings you want selected, press the green Start button. Note that you have to set the Scan button on the MF to Remote Scanner.
Howefver, the issue is not that I try to use MF Toolbox & it does not scan or cannot find the hardware. The issue is not that I am not pressing the Start or Scan button. The issue is that as soon as I *open* MF Toolbox, the software freezes up and gives a now-too-familiar "(not responding)" warning. This software appears to have conflicts with Mac operating system.
I could mention more fundemental things you're missing -- such as the fact that my MF4570dn is connected directly to my computer via USB and therefore isn't just having the network related issues that Canon acknowledges. But I think the above is enough...
I imagine there might be some software conflict going on between MF Toolbox & another application on my machine. Sure I could try a clean install of my operating system, or spend hours methodically trying to figure out which application might be conflicting with MF Toolbox. The question is why? I imagine 90% or more Mac users -- especially those who do any kind of graphic work and have applications like Adobe suite -- would rather get a different printer than devote several days to make this device work.
The one piece of advice I'd really love from you, or anybody, is what multifunction you'd recommend other than this Canon that is proven to work elegantly with a Mac OS 10.6.8.
Honestly, I am wondering if maybe you are an employee or Canon or do a lot of business with them and are defending them for that reason? That's okay -- as I've mentioned here & elsewhere, this multifunction device seems to be a laudable product. But just as clearly doesn't seem to work correctly on some Mac platforms as many users have reported.
Thanks