I use a SGH-i927 Captivate Glide (4.0.4 AT&T stock rom, rooted) which has a physical US-keyboard. I frequently type in my native language which uses letters with umlauts. I know the trick that keeping e.g. 'a' pressed for a moment brings up a popup that has different variations of 'a'. However, I find that very clumsy since it breaks my typing flow. I always use the same umlauted 'a' from the popup, so the other 8 variations of 'a' are useless.
What I'm now looking for is some kind of a shortcut to 'ä'. Ideal would be the same kind of behavior that can be seen with the top row of a virtual keyboard and its embedded numbers.
How can I make 'a' turn into 'ä' after keeping the key pressed for ~0.5 seconds?