𝑉_{𝑢𝑏} is the smallest and least known of all CKM matrix elements; it's currently determined primarily through the exclusive process B \to \pi \ell \bar{
u}. I will present progress toward a lattice QCD determination of the 𝑉_{𝑢𝑏} matrix element from a novel transition -- the B \to \pi \pi \ell \bar{
u} process, where the π π system is in a P-wave and features the \rho(770) resonance as an enhancement. The calculation is performed an ensemble with 𝑁_𝑓=2+1 isotropic clover fermions wiht 𝐿≈3.6 fm and a pion mass of 320 MeV; for the b-quark we use the anisotropic clover action. After a brief overview of the theoretical framework, I will discuss some preliminary results.