Typically, I split the buns open. I then jam the meat in between the buns because of the limited tight space. Because of this, quite often it's necessary to forcefully hold it between the buns with some moderate effort. I find that in these situations sauces can be quite messy and will run out of the buns. This is why I always ensure that I have plenty of napkins, paper towels, tissues, anything that is absorbent (perhaps a shirt sleeve) available to wipe up the mess.