As you know, BBC3 will be broadcasting the first hour of The Cure's set at Reading on Friday at 21:00. Problem is, if you're outside of the UK, you can't watch it online. So you will need a proxy/VPN. While there are other ways, the simplest way to set one up seems to be by downloading and installing Tunnel Bear. Have heard it worked very well during the London Olympics, and would expect it to be just as good for the Reading coverage, though there are no guarantees. This will be my first time trying it, so we'll see what happens.
If you want to try it, just go here, download the version that's right for you, install it, switch it on, set it for UK, go to the BBC Reading website, and try watching something that is live. You only have 500MB of free data, but do the Twitter promo and you can get an additional 1GB. That should be enough if you just want to watch The Cure's set on Friday.
After the 1st hour, The Cure's set is supposed to continue on the Red Button channel, though the BBC page doesn't mention this, only Radio Times. Then you can go back to BBC3 for highlights at 23:30.(Thanks to @rob_sheridan for the tip on this)
Update: "also expat shield works on the bbc" (Thanks Gary)