I managed to get all the wallpapers on the Xperia S (18 total) and resize them for the screen size of the Arc and any other phone with the same screen size (854x480).
There are two zip files. One just has the (resized) wallpapers, whereas the other zip file has wallpapers which you may place for the wallpaper picker.
Wallpaper picker set (Flashable CWM zip):
Mirrors (Box & Dropbox)
http://www.box.com/s/ea544f317ecac1a9e71a | http://db.tt/n3PbhqCk
Wallpaper picker set (Not Flashable, must be put into /system/etc/customization/content/com/sonyericsson/wallpaperpicker/wallpapers):
http://www.box.com/s/242494f8180a5ce3f3a1 | http://db.tt/QnT1LDXT