I recently found myself up against 3 combined challenges trying to get into my 2004:
1* super-locked
2* stone-dead battery
3* door lock linkage disconnected

When I figured out how to get in I thought I should share it, so I made this video:
Note: I left out the tool dimensions. I used an 18" piece of 1/8" drill rod. I bent 5/8" of the business end of it at a right angle, then marked 5 5/8" back from the end for my depth. I insert the rod just a couple of degrees left of straight up & rotate it so that the end faces away from me, toward the vehicle interior.

 

Nice, but you don't explain how you figured out this solution. Were you able to look at another DII to see the mechanism from the inside?

Also, why did you not connect jumper cables, a jump box or a charger to the starter terminal and frame to apply power to the system and use the keyless entry remote?

 

Okay, point taken. I left a lot out.

I did leave in the part explaining how to get quickly get into your Disco with a piece of bent wire and a screwdriver.