Front E-Brake Cable

I have a 73 Dart Sport that I'm looking at replacing the e-brake cable on. I'm concerned bout the front cable (the one from the cabin through the firewall) feeding under the floor pan. The manual essentially says that the new cable just feeds back under the floor pan. However, starting to pull the old cable, it doesn't feel like it's going to come through that easy. Before I pull the old cable out, I'm looking for feedback from folks that have done this. Does the new cable really feed through that easy? Are there any tricks to help it along?
Thanks FABO.
Foster.