I mean I like the sound of that, but it seems the long way round to get there. Plus I'm not really up for drilling. I think either the Di2 under the TT or a wrap around @gillies is right, I think there should be space under the frame pump as the pump contact points are very near the joints and with my Zefal there is a nice amount of room between the pump and TT. Maybe @gillies pictures and my experimentation will help you decide....
Yeah, I will almost certainly just run it along the top tube and it will end up hidden with a framebag anyway but it's nice to dream of hidden cables :)
I mean I like the sound of that, but it seems the long way round to get there. Plus I'm not really up for drilling. I think either the Di2 under the TT or a wrap around @gillies is right, I think there should be space under the frame pump as the pump contact points are very near the joints and with my Zefal there is a nice amount of room between the pump and TT. Maybe @gillies pictures and my experimentation will help you decide....