I just removed the dash, rewired the tweets and mids, and cut the old tweet pods out, and removed the tweet covers and mounted the new tweets in these holes. Sounds like a lot of work but well worht it IMO.
But yer they do twist off, its hard enough with the dash out but if you put two pins in the grilles im sure you could do it,
PS - removing the dash is allot harder than it says in the guide on the cliosport websie, plus there are only 12 screws that need to be removed. If you want a fuller description, PM me
Rorrie