The electrical properties of the lightning channel are determined by a complex interplay of dielectric breakdown, plasma heating, expansion, and cooling. These details are observable through their effect on the channel current and electromagnetic wave emissions. This suggests that electromagnetic observations of lightning can be used to study channel physics and behavior. This paper presents the Time Domain Fractal Lightning model (TDFL), a high-level tool that connects channel electrical properties to charge and current flow for branched, tortuous lightning channels. The TDFL extends ideas of fractal discharges to the time domain through the retarded time electric field integral equation. Here we present a preliminary application of the TDFL to stepped leader extension and compare the predicted electromagnetic emissions to observations. The results show crude qualitative agreement, demonstrating that more complex channel behavior should be included and that such behavior can be studied with high-level tools like the TDFL.