This document summarizes a study investigating parametric oscillation in the LiInSe2 crystal for mid-infrared wavelength generation. The study analyzes threshold intensity conditions for parametric generation in LiInSe2 under an experimental configuration involving a double pump pass through a resonator containing the crystal. Equations are presented modeling parametric interaction in the crystal using the constant intensity approximation to account for phase changes and losses of interacting pump, signal, and idler waves. Results are compared between the constant intensity model, constant field model, and experimental data.