Seen it when I lived in Puerto Rico - haven't done it myself. When I watched them do this on the beach, the fine cooks doing it did several things:
1) Shaved with a straight razor (for real) all the bristles off the face if they weren't removed
2) If they couldn't get them off with a straight razor, they used a small gas torch to burn whiskers/stubs off
3) I have seen them use a salt water or vinegar soaked towel to clean the whole head - including the ears.
4) I found out later (I'd only been on the beach while they were smoking it) that they also soak the whole head for about 2 hours in cold water. Apparently, most heads come salted and this removes some the salt and makes for a more consistent flavor. Once done soaking, they dry the head off with towels and put on a tray and leave in the fridge to dry for a day - the key, I'm told, to crisper skin.
5) Sometimes when the shack I went to was busy, they would have the heads sliced in half to cook faster.
Since this was on the beach, the head was buried in a sand pit smoker. A lot of picking, but pig's cheeks are all that.