Apertium on Arch Linux
Arch Linux users should follow Installation if they wish to develop/contribute to Apertium. Users who simply want to use the released translators can install packages from AUR.
Installing the released packages
yaourt -S apertium-eo-en
This will install both apertium, lttoolbox and apertium-eo-en in the /usr prefix. You can of course use your favourite AUR installation method (manual makepkg or other AUR Helpers).
If you have trouble, follow the instructions on http://wiki.archlinux.org/index.php/AUR#Installing_Packages_from_the_AUR. You'll find a list of language pairs in AUR at http://aur.archlinux.org/packages.php?K=apertium
Many language pairs are, however, not released and/or not available through AUR. For these, see Installation on how to install from GitHub.