This article was first written in March 2004 for the BeezNest technical website (http://glasnost.beeznest.org/articles/113)
You have to be root to do this, so be careful .
Edit the file evolution-mail-message.xml in /usr/share/evolution/1.4/ui/ or /opt/gnome/share/evolution/1.4/ui/ (depending on your distribution).
Search for example for MessageReplyList and add/change the accel-key you want.
Restart GNOME for the change to take effect.
Note: this example has been obsoleted by version 1.4.6 of Evolution, which already include it.