I don’t think it’s activated electrically, so you’d have to install an electric activator and a load of gubbins to force it to override, so it’d cost a lot more than 5p for the switch.
In the same way that having a lever to switch from SS to fixie on your bike would be a lot more difficult than fitting a lever.
I could be wrong though.
EDIT I do seem to be wrong, in fact, googling it.
EDIT #2 Ah, I may be accidentally right – I was thinking of the Haldex system used in many cars, which is in fact electronicall activated, but Honda CRVs up to 2012 use their own system which is in fact internally automatic and is activated by the differental speed of two hydraulic pumps:
http://www.awdwiki.com/en/honda/