It has to be said, they don't make it all that obvious what you need to do as an overseas seller to register an EIN.
It IS there. You just need to know where to look. And where is that? Why HERE of course.
That's not quite the end of it. You need to be able to answer the Form SS-4 Questions
It's a great fun form, but keep in mind that getting an EIN from overseas is very hard unless you have already incorporated a limited Liability Company (like a Pty Limited, Limited or PLC) in your own home jurisdiction. In the USA these are called LLCs and what you need is the overseas equivalent.
IMPORTANT Disclaimer: I am not a qualified tax advisor in the USA or any other jurisdiction for that matter. This article is only intended to take you to the right place and inform you about the basics from my own experience.
Please seek your own tax advice from someone qualified before you act. Feeling daunted? Calling the IRS directly is a good source of information and they are actually very helpful.