Instructions
Connect one end of the HDMI cable to an open port on your television and the other end into the back of the PS3.
Turn on the PS3, then click "Settings" and scroll down to "Display Settings."
Select "Video Output Settings," then choose "HDMI."
Check all resolutions your television supports when the resolution screen appears. Since you want to hook the PS3 up using 1080i, select only the check box next to 1080i.
Select your aspect ratio from the next screen. Choose 16:9 for high-definition viewing, then click "Save Settings" to apply your changes.