GA User ID Tracking

Wondering how to best go about implementing Google Analytics User ID Tracking in IPB4.

Is there a shortcode or something that I can easily add in the Google Analytics AdminCP section? Eg:

ga(‘set’, ‘&uid’, {{USER_ID}}); // Set the user ID using signed-in user_id.

or

ga(‘set’, ‘&uid’, <? echo $USER_ID ?>); // Set the user ID using signed-in user_id.

etc? Doesn't look like the Google Analytics section praises php code (probably a good thing), so any ideas on this would be great.