[en] In this article we present results concerning the extraction of light charged particle multiplicities in incomplete fusion-fission reactions with a moving source fitting procedure. To demonstrate the feasibility and reliability of the procedure we have used simulated events of known multiplicity to construct kinetic energy distributions at different angles that are fitted assuming several pre- and post-scission sources. In particular, we show that it is necessary to include at least two pre-equilibrium sources in order to extract correctly the known pre-equilibrium proton multiplicity. These two sources are characterized by high emission temperatures, low emission barriers and high velocities, having ∝70% and ∝25% of the beam velocity along the beam axis, respectively. The former source is naturally dominant at forward angles due to the strong focusing effect of its high velocity. Contrary to normal expectations, however, the slower pre-equilibrium source is present with considerable yield at the most backward angles θ∝145 where it is normally assumed only evaporative components are present. The extracted proton multiplicities are well reproduced by the moving source procedure, as well as fitting parameters with physical relevance. (orig.)