Surely it'll be exactly the same as the 4?
I have a brodit proclip in the C4 with a pass through holder. So I can put the phone into the cradle and it hooks up to the headunit.
Can just see it at the side here. Got mine from http://dsldevelopments.com/
Not the cheapest, but had a few brodit mounts and proclips now and they are good quality and no having to drill into anything.
That griffin one looks nice