Canadian English on Apple products

In Mac OS X 10.6:

1. Open up System Preferences
2. Choose the Language and Text Preference Pane
3. Choose the Text tab
4. For Spelling, choose Canadian English

Alternatively the instructions for 10.5 and earlier still works as well:

In Mac OS X 10.5 and earlier it's not very obvious:

1. Open up a Cocoa application such as TextEdit, Pages, etc.
2. Control/Right Click on some text and choose "Show Spelling and Grammar"
3. At the bottom there will be a selection of dictionaries - change it to Canadian English

This will only affect applications that use the OS X Dictionary. (eg. Safari, but not Firefox)

System Preferences > Language and Text > Text Tab

There is a spelling popup on the right that says "Spelling" where you can select the dictionary. There is a Canadian English option available. (Snow Leopard tested.)

On my system, I use "Automatic by Language" as the setting, and Canadian English in the language bar, and get the proper spelling for colour/labour etc. in spell checks (cheques, if you're talking about money. HEHEHE.)

Edit: As for iWork, you have to make sure the proper language is selected in your styles. In Pages, for instance, there is a "Canadian English" setting in the text panel, under the "More" tab.

Edit #2 OK, so you don't use Snow Leopard (if your system can handle it, get it! $30 is a bargain.) Here's another option.

Install cocoaspell and a canadian english dictionary is available on the aspell ftp site.