Five months after the first release, the QBoxHD Team has updated the repository in which you can get the stable and development source code of enigma2 and the kernel.
You can get the development versions from here:
svn checkout https://www.qboxsvn.com/e2-0.2/e2-0.2/branches/enigma_ng enigma_beta_qboxhd
svn checkout https://www.qboxsvn.com/linux-sh4-kernel/trunk /opt/STM/STLinux-2.3/devkit/sources/kernel/havana-linux-sh4
For getting the stable version see this previous post
One important thing that was added to their sources is a small package that contains the header files of the S2API adapted for the 18.104.22.168 kernel. This package contains the file stm_ioctls.h that was missing in the previous release and without it compiling enigma2 was not possible unless you commented part of the source.
You can get this package from here.
After downloading it, copy the uncompressed directory to usr/include/linux inside the filesystem
used for compiling normally located in /opt/STM/STLinux-2.3/devkit/sh4/target and
rename it to dvb.
At this point you can compile enigma2 as described in this post. Notice that you will need the 0.3.4 version of libdvbsi++. The rest of the libraries needed by enigma2 remains the same.