Where are the keymaps in Debian? (Using loadkeys to change keymap.)

1) Make sure console-data package is installed:

# loadkeys dvorak
Loading /usr/share/keymaps/i386/dvorak/dvorak.kmap.gz

$ dpkg --search /usr/share/keymaps/i386/dvorak/dvorak.kmap.gz
console-data: /usr/share/keymaps/i386/dvorak/dvorak.kmap.gz

$ cat /etc/debian_version 
wheezy/sid

2) IMHO, yes dumpkeys > test.keymap && edit test.keymap && loadkeys test is the easiest.