Even then he needs a developer account, so he needs to go and get one at the App Studio website first. Once your e-mail address is confirmed to be a developer address, you can now use the Developer Preview program on Windows Phone.
This will NOT get you Cyan, Denim or any Lumia Firmware. It is not optimized for your phone. Proceed at your own risk. May void any warranty express or implied.
I'm coming out against users joining P4D willy nilly just to get a shortcut. That is not what it is for. If you join the Preview for Developers program you should do your homework and be prepared to face bugs, glitches and other issues of running an un-optimized system. It will not break your phone, but it is not for casual users who are not tech skilled and willing to commit ongoing time to their device.
Proceed as you will...
<edit> Also it would take you past 8.1 to 8.1.1 so instead of optimized 8.0 + Lumia Black you would be on un-optimized 8.1.1 + Lumia Black. Expect a loss in battery run time at the very least.