Figured it out. Take the ground state of the harmonic oscillator \psi_{0} = A e^{-\frac{1}{2}\alpha^{2} x^{2}} and use the orthogonality condition \int_{-\infty}^{\infty} \psi_{0}^{*} \psi_{2} \ dx = 0.
From there just expand, cancel out A* and C, and solve the integrals with integration by...