How to add a set of keyboard shortcuts for document/text applications in System Preferences with Automator?
Follow this guide from Apple about how to make a system-wide service in Automator.

The service will not require any input, but should be made available in any application.

Add a Run AppleScript action.  Enter this code in the text box:

on run {input, parameters}

    tell application "System Events" to ¬
        return (key code 126 using command down) -- Command Up

end run


This is the AppleScript code that will simulate pressing ⌘+▲.

Save the service, naming it something like Command Up.

Finally, go into System Preferences and create a keyboard shortcut for this service.  It will appear towards the bottom of the services list:



Assign it the shortcut ⌃+▲ (ctrl+up).

Now, when you press ⌃+▲, the system will issue an automatic ⌘+▲ keypress, allowing you to hijack its function.

Now repeat the process for your other key combo.  The AppleScript for that one, which will be simulating a ⌘+▼, is:

on run {input, parameters}

    tell application "System Events" to ¬
        return (key code 125 using command down) -- Command Down

end run