Absolutely. Your CSLA business objects will sit behind the service interface. Take a look at the Web Service Interface chapter in the book and the ProjectTracker sample app for example code.
In its simplest form, you'd have a CustomerList that contains Customer business objects. Your service would "translate" the CustomerInfo data transfer objects (DTO) passed into the service method to Customer objects and populate the CustomerList then call the Save method on the list class. It really is that simple.
Hope that helps.