Here's photos I found on another forum of a Allez Sprint with Di2 install. It's a bit messy, but can work: https://imgur.com/a/xP5VyU6

I'm not totally clear if the disc version of this frame has ports for Di2 wiring or not, but since Specialized doesn't sell it that way I'm guessing no. There's talk on other forums of people drilling holes in the frame to accommodate. Sounds a little dicey to me, and a wireless option should definitely be considered.