Some more things that may be interesting:
XKEYCAPS http://www.jwz.org/xkeycaps/
xkeycaps is a graphical front-end to xmodmap. It opens a window that looks like a keyboard; moving the mouse over a key shows what KeySyms and Modifier bits that key generates. Clicking on a key simulates KeyPress/KeyRelease events on the window of your choice. It is possible to change the KeySyms and Modifiers generated by a key through a mouse-based interface. This program can also write an input file for xmodmap to recreate your changes in future sessions. <<
Also, in KDE, look at Kmenu->Configuration->KDE->Accessibility->Keyboard Layout->Options tab - there are options for compose key here amongst several others.
¥ée!
Syd