Zac,
there are basically, two ways they do the tongue, either, up through the bottom of your chin or what they did to me, was make me stick it out and stuck the needle right in the middle from the side. It actually, was the least painful of all the sticks in my body.
He then made me (yes, with the needle still in the tongue), pull my tongue back in my mouth and rest it for a few moments with my mouth closed.
it didn't hurt, the other sticks (arms and legs were worse..)
Don't get too nervous...it will go by quickly.
Good Luck,
Jamie