Alt vs Meta

[Mats Aigner]

Hello!

When running X, I have both an Alt and a Meta key. For various 
reasons I would like Emacs to treat the Alt key as Meta, and either 
ignore the Meta key or treat is as Alt. Is this possible?

(I don't want to change any keybindings with xmodmap. Other 
applications more or less determine which keybindings to use, and I 
figured it would be easiest to change Emacs behaviour only.)

Thanks in advance!

                        Mats Aigner