No different than servicing one that doesn't, though if the BB doesn't have a sleeve I'd make one. Dirt gets in around the spindle & drops out of the frame tubes as well as comes in through BB cutouts. I've made sleeves out of aluminum cans, plastic anti-freeze bottles and such. I never had much trouble with BBs, and once I started using Campagnolo (whose proprietary sleeves tended to split) I never had BB problems at all.