the bush comes in 4 parts
innder (the bit in the pic)
outer( not in the pic)
rubber outer (not in the pic)
metal spring clip (in the pic)

once the carpet is out and the intermediate sheeter shaft has been uncoupled you can just use a long screwdrive to punch the bits out
whenyou put the metal clip onto the shaft first make sure it's the right way in so that it locks on the way up not on the way down the shaft
then put the innder bit on
then the outer bit
then push the rubber seal up through the gap as well
now put the out bit of the bush into the rubber bit and then push it all through he bulkhead from insdei out
then the innder bit slide in and then the metal washer locking tab goes over the otp
you can always use a cable tie to clamp the shaft after th emetal clip to ensure it stays in place and, on some cars, there is also a metal collar that goes over the engine bay side of the rubber plug so make sure you put that on if it's there

think of this as a service item and replace it every eyar or so and you won't go far wrong