Internally routed cables…

I have heard that it’s a bit of a task to get the cables routed through the frame on the P3. Any tips from those of you that have done it before I attempt it?

Also, what do you folks use for cables? I’d like to use the same cables that came with the Dura-Ace kit but can’t seem to find Shimano cables—without the housing.

Thanks for any feedback!

Rob