1 - Select and copy this URL:

http://127.0.0.1:2400/AdKiller.pac

2 - Select 'Preferences...' from the 'File' menu.

3 - Go the Network section of the preferences.

4 - Click on the Proxy servers... button.

5 - Select 'Use automatic proxy configuration' (put a tick in the checkbox).

6 - Paste the URL (http://127.0.0.1:2400/AdKiller.pac) into the textbox under the checkbox:

Click OK to dismiss the windows, and the setup is complete.