How do you replace freeze plugs in a 289 ci?

The same as any other motor. Knock the old one out, clean the hole with some sandpaper and drive the new one in. You may have to remove a motor mount, or exhaust so that you can get a straight shot at it. There are two in the back of the block that require you to either pull the motor or the transmission to get to them. The plug is easy, getting to it can be a real pain.