Scenarios, represented using variants of sequence diagrams, are popular means to specify systems requirements. Live sequence charts (LSC), is a formal and expressive scenario-based specification language, which has been extensively studied over the last decade. Careful reading of the LSC literature, however, reveals many variations and ambiguities in the semantics of LSC, as it is used by different authors in different contexts. Moreover, different works define their semantics of LSC using different means. This variability, in both language features and means of semantics definition, creates a challenge for researchers and tool developers. In this paper we address this challenge by investigating semantically configurable analysis. We define and formalize the variability in the semantics of LSC using a feature model and develop an analysis technique that can be instantiated to comply with each of its legal configurations. Thus, the analysis is semantically configured and its results change according to the semantics induced by the selected feature configuration. The work is implemented and demonstrated using examples. It advances the state-of-the-art in the area of scenario-based specifications and provides an example for a formal and automated approach to handling semantic variability in modeling languages.