Whoa, they actually mean it when they write "wired by hand", not just
soldered to a pcb by hand:
,----[
http://www.maltron.com/maltron-kbd-flat-assembly.html ]
| The key-modules are then wired up in an XY matrix. Discrete wiring
| rather than a dedicated PCB is used as this allows complete
| customisation of the keyboard's switch arrangement.
`----
There's also picture in this article where you can see the wiring. It
looks like they use polyurethane enamelled wire to make this process
economically feasible.