I think you have to buy a MSDN subscription, buy you can try the Release candidate before it is released officially.
Go to your product keys page:
https://msdn.microsoft.com/en-us/subscriptions/keys/
If a key is listed for VS 2013 then you should be able to try it out.
You can download it from here:
http://www.microsoft.com/visualstudio/eng/products/2013-editions#d-professional
Then, after installing, instead of signing into your account, you can register the product with the static key.
Here is what MS says:
"The product key is not embedded with Visual Studio 2013. When you launch the product, you can simply sign in with the Microsoft account associated with your MSDN subscription and your IDE will automatically activate. An added benefit of signing in to Visual Studio is that your IDE settings will sync across devices, and you can connect to online developer services. If you’d rather enter a product key, then simply bypass signing in and enter the product key found here by selecting Register Product under the Help menu."