Does this include platform tickets?
You'd probably get laughed at if you asked for one of these from Merseyrail. For one thing they have enough problems issuing 'normal' tickets!
They have so few spotters though that they'd most likely just let you through if you asked nicely at the barrier. Make sure you get the name of the person who's there though as they might change staff while you're gone and may well think you're trying it on.
Alternatively, the distance to the next stations is very short and tickets aren't expensive so you could just get one of those and legitimately go through. I suggest Hunts Cross as this will allow you access to both lines (remember the two halves of the station are linked only by the main concourse so to get from one to the other you have to present tickets twice).