Music therapy addresses physiological, cognitive, and social needs of individuals and employs music to enhance quality of human lives through creation of positive changes. In this paper, we consider applying music therapy to human-computer interfaces, based on Quality of Life Supporters (QLS) of self-explanatory type, and oriented to elderly and disabled people. QLS are multi-modal communicators for person-environment (P-E) fit adjustments that take into account individual emotions and wellbeing. The "Circumplex model" published by Russell (1980) is employed for constructing optimal sequences of steps allowing smooth transition between any current and target emotional states in the course of computer assisted sessions. Findings regarding optimal step sizes and preferable types of music applicable for each step, as well as empirical methods of acquiring knowledge concerning relations between music and emotions are reported in result.