The best input method I have ever used (other than folding keyboard) is a program called 'FITALY'
It is a different keyboard layout, but after a few days of steady practice, it becomes very fast to input large amounts of text on the go (I work walking around. . .)
Fitaly has shortcuts and more shortcuts, and every umlaut or any other symbol you will need. Using a "tap-n-slide" technique with the stylus, you can decide to produce a capital letter, or any custom punctuation you choose when customizing Fitaly for your needs. You can also customize whole phrases to insert with two taps. This is a great tool for people who want to input a lot of text and just can't use a keyboard for whatever reason. It takes a little used to at first, but it is well worth it.
The link is
http://www.fitaly.com