After manually setting up a corners.inp, dxdy, lxly, and cell.map file, I found that I could import them into CVLGrid. I then saved them as a .cvl file and initiated a new model import in EFDC using the .cvl file. However, all of the dx and dy dimensions appear to have been reversed. Luckily, I could just replace the dxdy and lxly files generated by EFDC with my own and the model will run and display the correct dimensions.