xkb

sudo vim  /usr/share/X11/xkb/symbols/us
--------------------------------------------------
key <AC06> {    [       h, H, Left      ]       };
key <AC07> {    [       j, J, Down      ]       };
key <AC08> {    [       k, K, Up        ]       };
key <AC09> {    [       l, L, Right     ]       };

key <AC10> { [ semicolon, colon,     BackSpace ] };
    key <AC04> {        [         f,    F, Escape               ]       };
key <CAPS> {[ISO_Level3_Shift]};
------------------------------------------------------------------------
spare_modifier="ISO_Level3_Shift"
xmodmap -e "keycode 65 = $spare_modifier"
xmodmap -e "keycode any = space"
xcape -e "$spare_modifier=space"

http://kongjiaming.blogspot.co.il/2013/05/hjkl-for-direction-keys-in-ubuntu.html
https://github.com/alols/xcape