We develop a generic coarse-grained model for describing liquid crystalline ordering of polymeric semiconductors on mesoscopic scales, using poly(3-hexylthiophene) (P3HT) as a test system. The bonded interactions are obtained by Boltzmann-inverting the distributions of coarse-grained degrees of freedom resulting from a canonical sampling of an atomistic chain in circle minus-solvent conditions. The nonbonded interactions are Oven by soft anisotropic potentials, representing the combined effects of anisotropic pi-pi interactions and entropic repulsion of side chains. We demonstrate that the model can describe uniaxial and biaxial nematic mesophases, reproduces the experimentally observed effect of molecular weight on phase behavior, and predicts Frank elastic constants typical for polymeric liquid crystals. We investigate charge transport properties of the biaxial nematic phase by analyzing the length distribution of conjugated segments and the internal energetic landscape for hole transport. Results show how conjugation defects tend to localize near chain ends and how long-range orientational correlations lead to a spatially correlated, non-Gaussian density of states.