These two custom keyboards might be useful for one or the other. They are based on the regular OS X German keyboard layout but with slight modifications to accommodate transliteration of Arabic/Persian/Turkish etc. texts. They work with DMG and MESA style of Transliteration. Use the keyboard viewer to find the exact position of the keys. The second layout is useful for Latex & friends. If you want to use these layouts put them into ~/Library/Keyboard Layouts/