Custom keyboard layout: UK international with AltGr dead keys

readme.txt

from: http://ubuntuforums.org/showthread.php?t=1654199&highlight=.Xmodmap

sudo cp gbaltgr /usr/share/X11/xkb/symbols/

edit /usr/share/X11/xkb/rules/evdev.xml, just before </layoutList> insert:
    <layout>
      <configItem>
        <name>gbaltgr</name>
        <shortDescription>en</shortDescription>
        <description>English (UK, international AltGr dead keys)</description>
        <languageList><iso639Id>eng</iso639Id></languageList>
      </configItem>
    </layout>

Then log out and back in

gbaltgr

partial alphanumeric_keys
xkb_symbols "altgr-gb" {

   name[Group1]= "English (UK, international AltGr dead keys)";

   include "latin"

   key <TLDE> { [     grave,     notsign,      dead_grave,            bar ] };
   key <AE01> { [         1,      exclam,      exclamdown,    onesuperior ] };
   key <AE02> { [         2,    quotedbl,  dead_diaeresis,    twosuperior ] };
   key <AE03> { [         3,    sterling,   threesuperior,  threesuperior ] };
   key <AE04> { [         4,      dollar,        EuroSign,     onequarter ] };
   key <AE06> { [         6, asciicircum, dead_circumflex,       onesixth ] };
   key <AE07> { [         7,   ampersand,       dead_horn,        onehalf ] };
   key <AE08> { [         8,    asterisk,     dead_ogonek,  threequarters ] };
   key <AB08> { [     comma,        less,    dead_cedilla,  guillemotleft ] };
   key <AB09> { [    period,     greater,  dead_abovering, guillemotright ] };
   key <AB11> { [     slash,    question,    questiondown,         degree ] };
   key <AC11> { [apostrophe,          at,      dead_acute,     dead_caron ] };
   key <BKSL> { [numbersign,  asciitilde,      dead_tilde,     dead_breve ] };
   key <LSGT> { [ backslash,         bar,       brokenbar,      brokenbar ] };

   include "level3(ralt_switch)"
};