Pearlized finishes are great! It would certainly add another dimension to your daughter's pink walls. Rubbing them on with cheesecloth or any other rag is a great idea, but you could also try blotting on the finish with a sea-sponge for a really neat, almost spotted look; I've done this with a gold-colored pearlized paint over pale yellow walls. It sort of looks like leopard spots, but is much subtler. You could also apply the pearl finish with a roller in a floor-to-ceiling section about 2-3 feet wide and then slide a rubber-toothed 'rake' painting tool down the wall to create a striped look. Or apply with a roller and go over it with a rough-textured brush to give finer vertical stripes...So many options!