Before compiling anything, take a look at the Makefile in FUSD's home directory. Adjust any constants that are not correct. In particular, make sure KERNEL_HOME correctly reflects the place where your kernel sources are installed, if they aren't in the default location of /usr/src/linux.
Then, type make. It should generate a directory whose name looks something like obj.i686-linux, or some variation depending on your architecture. Inside of that directory will be a number of files, including:
Compilation of the kernel module will fail if the dependencies described in the previous section are not satisfied. The module must be compiled again Linux kernel must be v2.4.0 or later, and the kernel must have devfs support enabled.