We address turbulent scalar mixing with a prescribed mean scalar gradient in the implicit large-eddy simulation (ILES) context. The focus is on the performance of ILES to capture the mixing dynamics due to large-scale entrainment and intermediate scale convective stirring in forced compressible isotropic turbulence. ILES is based on a multi-dimensional flux corrected transport algorithm with separate low wave number forcing of solenoidal and dilatational velocity components. ILES is shown to capture dominant aspects of the mixing transition as function of effective Reynolds number determined by grid resolution.