We introduce an analysis method to measure elliptic flow (v_2) fluctuations using the PHOBOS detector for Au+Au collisions at sqrt(s) = 200 GeV. In this method, v_2 is determined event-by-event by a maximum likelihood fit. The non-statistical fluctuations are determined by unfolding the contribution of statistical fluctuations and detector effects using Monte Carlo simulations(MC). Application of this method to measure dynamical fluctuations embedded in special MC are presented. It is shown that the input fluctuations are reconstructed successfully for <v_2> >= 0.03.