Instructions
Pull your TV away from the wall, and examine the jacks on the back or side of the television. Plug the AV cords into the HDMI jacks that connect to the cable box. This means when your box is turned on and playing, your TV must be tuned to HDMI.
Plug the cable wire from the wall into the television's cable jack.
Plug your PS3 into a different input jack on the back or side of your television. Match the colors to the jack, in an input such as Component 1 or AV. You can then run the PS3 and cable box at the same time. However, each will appear on a different channel.