Need program like "AllChars"

Hi. I need to be able to input composed (accented, etc.) characters in
linux. I'd really like to have a program that works exactly like
"AllChars" for Windows
It would be really great if it could work in X as well as the console,
or via remote sessions, etc.

I suppose there's a "linux" way of doing it. My keyboard is a regular
US 104-key, and my system locale is "US English", but I need to be able
to type European languages with a minimum of fuss, especially French.

The only way I can do it right now is to either copy and paste from a
character map, or set my locale and hunt and peck on the keyboard, or
else run Windows under VMWare and use AllChars.

I think what I'm looking for is a "Compose Key" input method.

For instance the way AllChars works to input "e aigu" : The user
presses and release a Ctrl key, then types "e '" It's very efficient,
and part of my typing habits already. Can I make linux do it the same?
If not, how close to that can I get?