3 words: DON'T DO IT.
There's nothing in the manual that says you have to use 220 or 240 volts, and the dealer never said anything about it, so I always just charged with the 110/120V in our garage. Even after my wife raised the alarm one day about the smell of burning plastic, I still kept using 110/120. However, I replaced the spade connector with the most robust spade that the local electronics store could find (ie, the same as the stock item). But the male Zero plug still got extremely hot (ie, my finger starting to burn after a second or two), so I tended not to charge until the battery got low, and I checked the condition of charge every hour or so until the battery was fully charged. And my wife kept nagging me about the possibility of burning down the garage.
And one day, after limping home with only one bar on the speedo, I noticed that the bike no longer was able to charge up to 11 bars. Now it was only 8 bars maximum. (I did a whole 'nother thread on that, with the title "how bad is my battery").
Suffice it to say that I eventually got a 240v system installed in the garage by an accredited electrician. I didn't bother to get a wall outlet done, but instead just soldered the wires to the female plug end of the original Zero cord. I did, however, get the electrician to install a robust switch for the cord, so that any sparking during the on/offs occurred at the new switch, instead of at the bike plug. And the whole thing cost me less than $200. I only wish I had done it when I originally purchased the bike.
Now, not only does the plug on the bike remain totally cool, but I've also found that the balancing function (p. 6.4 of the manual) on the BMS actually works. In fact, the majority of the work done to get back to 11 bars from 8 was done merely by leaving the bike plugged into 240v for about a week steady.