Download the language selection tool
here
Open the file in a text editor and replace the variables near the top with these ones below, then run the script from a root console like this:
sh gtk-language-selection-tool
export wrk=/tmp/lst_wrk
dir=$wrk/build
repo=
http://dl.porteus.org
link=$repo/$arch/archive/Porteus-v2.0-i486/current/packages/Language-Selection-Tool/
kdelink=$repo/x86_64/archive/Porteus-v2.0-i486/current/packages/Language-Selection-Tool/
nlink=$repo/i486/archive/Porteus-v2.0-i486/current/packages/Language-Selection-Tool/
icons=/usr/share/pixmaps/porteus
dump=$wrk/.dump