Freelander Gas Cap Lock Removal/Replacement
Not sure if you figured it out, but for the benefit of others I thought I should post my findings. I have a 2004 Freelander HSE and just did the fuel cap switch-out.
There are pretty much 5 main parts to the gas cap:
(1) the top of the cap
(2) the bottom of the cap which spins and secures the plug in place
(3) a big spring inside the bottom of the cap
(4) a little black locking tab at the bottom the cap bottom (more on this later)
(5) the lock cylinder/key mechanism
To get the key cylinder out (obviously the cap is off the car and the key is still in the lock), you press the bottom on the cap (#2) in against the cap top (#1). You'll see a little notch in #2 that allows a small tab from #1 to fit in, locking the two together. This lets you turn the key a bit more (counter-clockwise) and releases a small internal locking tab (#4), which allows you to pull the cylinder out. Keep in mind that #4 actually holds #1 and #2 together, so be prepared so you don't lose the spring (#3) in case you want to keep the old cap.
When you pull the cylinder (#5) out, you'll see #4 still attached to the end of it. Simply pry it off with a small screwdriver and then push #5 into the new gas cap (take a look inside the new cap to make sure you're lining up #5 to clip into the new #4, which is already inside the new cap).
That should take care of it!