how do i replace the spare wheel lock on my nissan navara?

the key adapter for my spare wheel is missing so i cannot crank the spare wheel down from underneath the car i have bought a new adapter but have to change the receiver as well as the spare wheel is still in position i cannot get at th crank in order to change it .having spoke to nissan they said it is a matter of removing the splitpin out of the old one and put the new one on but i cannot get at it because of the spare wheel that in front of it