I had my daughter at the hospital and had some perineal/labial tearing. They used newborn disposable diapers (pampers "swaddlers," to be precise) and sort of tore/cut them open at the top/front, then put crushed ice inside somehow (I'd have to be looking at a diaper, I think, to remember exactly how this worked). Anyway, it left the absorbent part of the diaper to absorb blood, but kept ice on my swollen perineum/labia. It was rather nice.
The midwife I work for occasionally uses the "twist-to-activate" ice pack pads when a woman has swelling. She cautions women that icing the area too much can slow healing (by inhibiting blood flow to the tissues), but in cases where swelling is severe or a woman is particularly uncomfortable, they are very useful.