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Hm...There was a update package for 2.6.2>2.6.3 however since it's really outdated version, then I'm not sure if I'll be able to find it. I think you can simply install the whole JomSocial 2.6.3 package, and then proceed with the other steps of upgrading.
Eh as far I can see, you now updated the thread's name...Before that it was 2.6.2>2.6.2 so I was assuming you want to upgrade to the latest 3.1.0.2 version. But if you want to upgreade only to 2.6.3 then you can simply install the 2.6.3 package, and it should do the trick.
Thanks Chris. And if I do want to upgrade from 2.6.3 then I use the iJoomla installer? But where do I get that? The download link on that "upgrade from old versions" page doesn't lead anywhere.