I just wrote up a 'How to Modify a Spring RC SM-S4505B Servo For Continuous Rotation’
The servo that available at GHI store
It’s really easy, took me about less than ten minutes, and nothing to solder or add into!
Hoping that this would be a good tip for someone else that want to build a robot using the Servo instead of Motor.
Here is the link to the Wiki page.
And the video!