There were lots of disappointed folks when the last round of Lego Ideas reviews came in and the Team BTTF Jules Verne Train did not make it into the production phase. Thankfully, they have released the building instructions for Lego Digital Designer in both Locomotive and Power Functions forms.
Once you create a build guide in LDD, the last page of that guide will give you a parts list of everything you need to construct the train. Then it is as easy (or hard) as sourcing all the elements you need from Lego Pick-A-Brick and/or Brick Link. I can guarantee that not all of the elements necessary are available on Lego's online store, so you will have to navigate the nightmare which is buying brick on the grey market. I can think of few things that I hate doing more.
They've also released the following video showing you how to modify your locomotive mode Jules Verne Train to accept the power functions elements.