Solution for all PC programs:

 

You can always enter the ASCII codes for German Special Characters by holding down the ALT-Key, then entering in the number code for an individual character.

The following chart gives the codes for the German special characters.

 

ALT + 129 ü
ALT + 132 ä
ALT + 148 ö
ALT + 142 Ä
ALT + 153 Ö
ALT + 154 Ü
ALT + 225 ß
ALT + 0128

 

These will work for all programs, including web-browsers.