Yes. You can either build a custom kernel based on GENERIC by adding options PAE. Or, you can just compile the PAE kernel config file that ships with FreeBSD.
However, long-term, you are better off installing the 64-bit version of FreeBSD, as not all drivers will work with a PAE kernel, and things will not be as stable as a pure 32-bit (non-PAE) or pure 64-bit install.