You need scons[1] to build the frei0r plugins. 

Building all frei0r plugins is triggered by:

$ scons


Use the following command to install the plugins at the systems default
location. You'll probably need to be root for that.
 
$ scons install

You need to set the "instdir" property to install the
plugins at a different location

$ scons instdir=$HOME/.frei0r-1/lib install

Note1 : if you have libgavl, you can edit the SConstruct file to also
build the scale0tilt filter.

Note2 : the filter 'facedetect' is not yet included in the scons build system.
It depends on the OpenCV library.
To build it under unix, change directory to "filter/facedetect", adapt
the Makefile (set the variable OPENCV_PREFIX) and build using "make".

[1] http://www.scons.org