PowerBook G4 Aluminum 15" 1-1.5 GHz Upper Case Replacement
"Forward" (step 10) means toward the front. I was not able to release the latch this way. However, I did eventually release all three latches at once by very slightly lifting the rear of the cover and pressing the cover back toward the screen.
It is not necessary to remove the trackpad and keyboard cables (steps 12, 13, and 14) to replace the hard drive.
PowerBook G4 Aluminum 15" 1-1.5 GHz Hard Drive Replacement
These are the 6 mm silver (not stainless) screws. Don't use the longer 9 mm silver screws (for battery compartment) by mistake and have to take everything apart again to retrieve them. Like I did of course.