Well, you can't:
- transition to a project manager instantly
- transition to a project manager while doing nothing
You have to first understand that a project manager is a higher position than that of a developer, and it needs skills different than those needed for a developer, that's why you should aim a bit lower. You should think about assuming the role of a project manager assistant (which is more or less a secretary to the project manager). The project manager assistant will help in almost all the project management activities, and will take over routine tasks from the project manager (such as simple status reporting). Now how can one be a project manager assistant? Well, just tell your project manager that you need to help him in his job while at the same time working as a developer (a developer is more highly paid than a PMA, so you don't want to completely transition into a PMA). The Project Manager will most likely agree if he doesn't have an assistant yet, and will start delegating tasks to you, and you'll start seeing the big picture in project management, and what project management is all about. One you're an experienced PMA, then the road will be much clearer for you on how to become a PM from there.
Now about the skills required you need:
- The will to become a project manager and the will to do anything to become a project manager.
- All the project manager qualities: People skills, communication skills, organization skills, etc...
It'll usually take about 2 years if you follow the above plan.