Kenzo is a symbolic computation system devoted to Algebraic Topology. It has been developed by F. Sergeraert mainly as a research artifact. The challenge is now to increase the number of users and to improve its usability. Instead of designing simply a friendly front-end, we have undertaken the task of devising a mediated access to the system, constraining its functionality, but providing guidance to the user in his navigation on the system. This objective is reached by constructing an intermediary layer, allowing us an intelligent access to some features of the system. This intermediary layer is supported by XML technology and interplays between a graphical user interface and the pure Common Lisp Kenzo system.