Keyboard-fix is a project mainly written in C, it's free.
A daemon that automatically replaces "ae", "aa", and "oe" with their respective Danish counterparts.
Replace ae, oe, and aa with their Danish one-letter counterparts in any program.
The program runs as a daemon, so you could start it on boot or whenever you need it. Yep, it's entirely up to you.
Just type make to compile!