How do I navigate to Mouse & Trackpad in Accessibility Settings with AppleScript?
You don't need UI Scripting to be able to do this.  System Preferences has an applescript dictionary that allows you to open up specific preference screens (panes) and specific items in the table (anchors).

tell application "System Preferences"
    reveal anchor "Mouse" of pane id "com.apple.preference.universalaccess"
    activate
end tell


Will open up the mouse and trackpad section. I found this by looking at the AppleScript dictionary for System Preferences, and some googling took me to an excellent discussion of using these commands.