Mostly one doesn't. Cleaning is highly dependent on the condition of the quilt. If it is in good shape you can vacuum it with a piece of window screen between the fabric and the dusting hose. You can also try spot cleaning with a damp towel.
DON'T get it wet, don't soak it, and for god's sake don't put it in the washer, you're likely to destroy it.
DON'T get it wet, don't soak it, and for god's sake don't put it in the washer, you're likely to destroy it.