Exploiting the potential of the internet economy demands innovative business models and versatile information systems. This requires a painstaking process of designing the future shape of a company and its information system. The realisation of cross-enterprise business processes requires the coordination of corresponding activities with customers and suppliers. An ever increasing number of new technologies and prospective standards makes the implementation or configuration of supporting software more and more difficult. To make things worse, most projects that are aimed at developing e-commerce systems are suffering from serious time pressure. This is too much of a challenge for many companies. This paper presents a method, called E-MEMO, that facilitates the design and implementation of e-commerce systems. It extends an existing method for multiperspective enterprise modelling. The method includes a set of special purpose modelling language and a process model. E-MEMO also provides a set of re-usable generic conceptual models for more efficient support. With respect to new business models and the design of new information systems, models of business processes are pivotal. However, their customisation is hampered by serious obstacles. E-MEMO includes an approach to customize generic models of business processes for e-commerce systems that is based on template-based refinement.