You want to set the deafult character encoding in the gnome terminal.
Here is a relaed issue:
http://www.linuxquestions.org/questions/history/323706
Here's more direct...
http://mail.gnome.org/archives/gnome.../msg00200.html
Apparently unrelated issues can hold clues... like:
http://www.ncst.ernet.in/projects/in...i-HOWTO-3.html
Seems you can change encoding with the default locale - see man locale for details.
However, in general, it seems gnome dosn't want users setting up broken processes by changing the default encoding.
However: you question says "wrong charset". Are you sure it is the encoding you want to change? Perhaps you want to change the font (edit profile)? Though I admit that anything other than UTF-8 as default is odd ...