How do I remap my capslock key to be alt + tab?

use xsetkbmap or xmodmap

Here is a quick into I have written no avoid forgetting how I did it. I wont tell you how to map those specific keys, but you will be well on your way. There are links to more thorough documentation.

umm... the link: http://genja.org/wordpress/2010/10/setxkbmap-genja/

You need something like the contents of /usr/share/X11/xkb/symbols/compose: partial modifier_keys

xkb_symbols "caps" {
    key <CAPS> { type[Group1]="TWO_LEVEL", [ Multi_key, Multi_key ] };
};

partial modifier_keys
xkb_symbols "102" {
    key <LSGT> { type[Group1]="TWO_LEVEL", [ Multi_key, Multi_key ] };
};

partial modifier_keys
xkb_symbols "paus" {
    key <PAUS> { type[Group1]="TWO_LEVEL", [ Multi_key, Multi_key ] };
};

partial modifier_keys
xkb_symbols "prsc" {
    key <PRSC> { type[Group1]="TWO_LEVEL", [ Multi_key, Multi_key ] };

.. just study the links I gave you and the world will be under your domination in no time!