For people that are not aware, you can get it from extra-devel. It's totally optified and will take around 300Mb on the "opt" partition (home partition). If space is needed ( and for better in-game speed, because some textures seems slow to load from eMMC ) you can move the folder "/opt/maemo/usr/share/wesnoth" to an microSD card, then symlink it from the microSD to "/opt/maemo/usr/share/wesnoth".