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


Building all frei0r plugins is triggered by:

$ scons


Use the followind command to install the plugins 
at the systems default location. You'll need to be
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


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