If i recall, Large flat head screwdriver or pry bar between the collared portion that mates up with the box and the green cup section, leverage against the box itself. Be careful but firm... It will come away. I think this is also covered in a manual conversion thread or similar somewhere will see if I can find a link.
How the fuck did you replace the boot without removing the drive shaft? Ive already pulled mine out but am trying to figure out how it goes over the knuckle