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 [1]. 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.
[1] see also Why using root on UNIX is bad ?