The main trick is to strip the wheel as far as it can be stripped ( clips and screws )
Then the cover can be fitted and stitched on.
Finally you re-install the spoke trims etc so they cover the edges of the new cover.
This covers the ND wheel - https://www.youtube.com/watch?v=cbGh_CKvxhU
Just found this video for the NC.
Can the plastic trims on the spokes be removed with the wheel in place or does it need to be removed? Or is it just easier to leave them alone and push the cover behind with the tool?
The spoke covers are screwed on from the rear, you can get at the screws once that black shroud has been removed from the rear of the wheel. Which means if I remember correctly, steering wheel off.
The plastic silver covered trims on the spokes are clipped and glued on to the black plastic mounts. I painted mine a different colour, the clips (plastic) are fragile and they will need to be glued back on too but you probably won’t need to strip them down that far for a wheel recover.