If you are here you're probably thinking of going to the States to attend a funfly or just to visit and might fly while there and are already aware of the new FAA rules. By now you've realized you still can't access the registration site if you are not physically in the States. You can get here https://www.faa.gov/uas/registration/ but when you click the register button at the bottom you cannot get here https://registermyuas.faa.gov/ . If by chance you can indeed access the page then you can stop reading now and carry on.
The workaround is to use a proxy server in your browser. I just go to this list https://www.us-proxy.org/ and choose one. I prefer to use a https:// one. If you don't know how to use a proxy I suggest googling the steps for your specific browser. Once you can get to the actual registration page you can create a new account and continue on with the registration. The good news(?) is once you've connected they now have most countries listed for your home address and billing address so it's painless. You do have to use a credit card though and it's $5.00 USD and good for 3 years.
If you don't want to do the proxy workaround you can wait until you get into the States and register then from a hotel computer, friends house, phone, etc. Or have a friend in the States register for you if you trust them with your credit card info. Do you trust them that much?
Personally I went ahead and registered from my home in Canada simply because I don't want to risk dealing with an over zealous border guard when I enter the States and they ask me where I'm going and what I will be doing. I know it's not likely they've even heard about it but you never know. Right?
Now do you really need to even do this? According to the FAA you need to be registered with them if you plan on flying anything outside above U.S soil that weighs more than two sticks of butter. Is the club or event you're attending going to require it? That's something you will have to find out.
Also keep in mind this does not take the place of an AMA or MAAC membership if the club or event requires it. Good news for Canadians is every event I've attended honors our MAAC membership in leiu of AMA. I think almost all of them will but I would ask ahead of time to be sure. Anyone outside of Canada or U.S. should find out more information regarding your own circumstances.