Verified and it is possible to apply skins even if you don't have Beta, however it's going to cost money. To be exact, two copies of Minecraft Beta will need to be purchased.
Not asking for donations (although they're nice if you do
), just thought i'd let you know.
For those wanting technical details:
The hack is a similar process to using bots. If you can create a bot with the same name as a player, it will have their skin applied to it. A bot called ZionFox will have my skin applied (whatever i have it set to).
I've registered two new users, called Team_Red and Team_Blue. If these accounts had ability to upload skins, and you 'spawned' with thier name (custom name tag), you essentially get their skin. This method is used on multiple servers (i had to try at least 10 times to get a name that wasn't taken), so it's definatly possible.