You will need to do some programming, as there is no program that implements that. What is already available is the package keyboard-shortcuts (in my repository). After you install that (and set the gconf key /apps/osso/hildon-desktop/key-actions/home_contacts_phone to false). Pressing 'o' on the desktop opens the browser at page www.google.com.

You can edit the python program /usr/bin/keyboard-shortcut for changing shortcuts. Reading this program should give you enough information to implement two letters shortcuts.