How to rebuild kernel ?
Recently I installed pfSense 2.3. Immediately the question arose kernel build. The study of the system I did not find the package manager, or a compiler (gcc or no clang) and the kernel source code. Now I speculated how this can be done, or you can even do it?
Sounds like you want a FreeBSD host, not pfSense:
Yeah would not really be a good idea to go about messing with the compile of your firewall kernel on special use distro like pfsense. If there is something specific you would like to see included or excluded from the kernel best to put in a feature request to the dev's.
If you want to compile stuff in general for freebsd, prob best to fire up generic freebsd install for such play. Not something that really should be done on system used for your firewall, etc.