Woopsi::XL is a collection of classes (libwoopsixl) that enhance the woopsi library in a few areas 
(freetype fonts classes, xmlbox : a widget with xml and css rendering capabilities, some containers, ...).

Some pre-compiled libraries are needed to build Woopsi::XL : 
freetype 2,

At the moment, some precompiled libraries among those are distributed by Woopsi::XL but this will be phased off as 
they are now distributed by the portlibs section of devkitPro (this is as it should be) : 
See in the portlibss folder

Also, if  you need up to date libraries, you'll find porting instructions and information about portlibs here :

To compile Woopsi::XL, you need bison (2.4.1 or later) and flex and to set up their path in the main makefile buildin Woopsi::XL
Look for the following lines 
export BISON:= bison
export FLEX:= flex

you may have to change the paths to the right and/or to put the binaries for bison/flex in your PATH environement variable. 

You can find windows binaries for bison (2.4.1) and flex (2.5.4a)  here :

Make sure you set them up in folders that don't have long names 
(i.e. for example, not in the program files directory)