I couldn't figure out how to 'slide' the Bluetooth board out, so I just left it in place and pulled the hard drive out.
The way I did it was to lift the back to about 45% (the ribbon cable is long enough) and then used the spudger to force the 4 snap tabs in front of the optical drive to separate, working from the right edge towards the middle (they will 'pop'), ending with the last tab to the left of the sleep light.
When putting the rings back you will need to figure out their correct orientation. Just rotate each ring until you find the position that will make it flush with the case. There are three possible positions but only one of them is the right fit.
I skipped this and the next step altogether. Instead of taking the risk of breaking the power and/or speaker sockets, I left them connected. I put a stack of big books just to the left of the iBook. I swiveled the top case off and let it lean against the books. I removed the top shield and carefully swiveled it off and to the left, so it is now leaning on the top case. I had to move the power cable out of the way, and re-orient the top case so it's resting on it's back edge while the shield was resting on it's left edge. Then I slid the iBook towards the edge of the table and disconnected the HD ribbon from below! I then proceeded with removing the HD and putting in the new one.