To become a registered PlayStation developer and gain access to the PlayStation Modules you need to first request to become a PlayStation Partner. You can sign up here. This gives you access to everything you need from Sony Computer Entertainment (ordering dev kits, downloading SDKs and tools, etc).
Once you have done this and have access to SCE DevNet, you will need to log in to the DevNet website and go to:
Development > Tools & Middleware
Click Tools & Middleware directory
Find GameMaker: Studio in the Engine Category and click "Confirm developer status"
Finally, click "Confirm status"
Please note: You will need to do this for each platform you are eligible for (PS4, PS3 and PSVita).
This will then notify us via email and we shall then contact you through the Helpdesk system. When we contact you, we will give you access to the Sony PlayStation module that you requested (please note that you must also have an active Console licence on your account to have access), the ability to see the console articles/forums here on the knowledge base, and access to report issues directly to the Mantis bugs database for GameMaker: Studio and the console-specific projects.
Please be aware that we cannot issue you with any information until you have been approved so please make sure everything has been set up before contacting us.