Registration is open quite often, actually. It's at random times, so the staff doesn't choose when it's open and when it's not. Hence, no reason for timezones to clash because it doesn't open according to any timezones. I believe having it closed most of the time is working well so far, and we aren't going to be changing it any time soon.
Your friends that wish to register will just have to keep checking back until they happen upon a slot when registration is open.
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Here's a list of dates that it has been open so far (just to show you how random it is):
2012-10-02
2012-10-07
2012-10-12
2012-10-20
2012-10-21
2012-10-22
2012-10-23
2012-10-24
2012-11-01