The source code is available on my github at misc-common/aesfs. To build just run 'python build.py' and the result is placed in ./build/aesfs/ and ./build/aespack/. AesPack is a command line utility to pack and unpack single files, while aesfs is a fuse file-system.
You can run aesfs with:
aesfs -o root=/my/plaindir /mnt/encrypted
Since AesFS is on top your file-system you've to specify (with -o root) the directory where you want to store files, while the /mnt/ is the mount point where you can read/write your files in clear.Files are written in blocks of 4k (8 bytes of header, 16 extra bytes for aes, and 4072 bytes of data). Check block.h and block.c for more information.