Actually, its pretty easy to do, sans instructions. Flip the latop over. On the right side where the audio ports are, you will see a single screw. It is not recessed at all. This is the screw that holds the HDD in place. Remove this screw and pull the assembly out carefully, away from the machine.
That's one thing about ThinkPads that make them extremely easy to work on: Accessibility ....
Let me know if you need more assistance. I have an electronic copy of the service manual in PDF format if needed.
Matt