I would love to be a UK/Europe Tech - did some time a bike mechanic when I worked in a bike shop and love all things electrical so between the two - would be a great part time job :)
Surely Onewheel could organise some training videos, maybe and have a direct hotline (Skype or other voip number for us to get in touch with them with any issues - kind of like the red phone the early apple store genius bars had)
We could have end user swap items sent out to us in bulk so foot pads and end caps, we could then mail them out and avoid the larger shipping costs (it must be cheeper to send over a few boxes full of stuff and then mail out individual bits within the country (or trade block (eu)) - Onewheel could email out a dispatch list at the end of every day perhaps, It would get rid of the unease of customs and duties, and make the shipping seem more reasonable (even if it seemed to cost a bit more due to the taxes paid upfront). (It would also be nice if we could pay in local currency)
We could have the tools needed for calibration, I am assuming a custom cable and some form of levelling device, and other more complicated repairs along with the necessary supplies so wheels and batteries for swaps, I am assuming that due to the motor design its unlikely errors occur here often, but perhaps a spare hub or two, with the old ones being sent back to hq for refurb process. Maybe wait a while to send one package with a few items at once.
As I said earlier I would love to be involved in this - I am not sure on total numbers but with 500 sold on Kickstarter, a more pottering round in garden shed approach - a self sustaining hobby model - is perhaps the way to go, rather than a more full time business model - more hobbyists being trained up to help other hobbyists, with some monies to compensate for time - as numbers of users in the country rise, get more techies in the area, maybe the first could train up the second.