The overall objective of the research activity of the UP1 unit is to apply a method engineering approach to the Lyee methodology. This paper presents a formalization of the Lyee Process Model using the concept of Map. It develops also two methodological guidelines supporting (i) the mapping of the Lyee user-centric requirements, which have been previously specified using Design Patterns, into Lyee software requirements and (ii) the optimization of the latter. The motivation is the search for efficiency and effectiveness in the formulation of requirements in accordance with the two levels Lyee Product Meta-Model. The pay-off will be a more productive process of requirements formulation and a better quality result.