We all know code is given, and cannot be created by one’s will.
Even being the Master Chief and all this will be a serious task to undertake. A lot of Halo 5 is built using Havok, this post should shed some light on what it takes to bring Havok into the UE4 realm of awesome : Unreal engine 4 + havok how to? - Community & Industry Discussion - Unreal Engine Forums
In essence you would have to have access to the Havok source code (Even though she has been in a bit of a rampancy-rage mood as of late, I am sure Cortana would help with this for ole times’ sake) and then it would need to be ported over to C++ with UE4 markups. You could then create a plugin which uses the Havok physics engine. Though this may be more than a headache if you ask me.
If you had the meshes/model source files importing them would be fairly straight forward, again gaining access is somewhat listed as one of your specialties. The import process is really simplified you can basically drag and drop into the content browser. Setting up materials will take some time though because 343 (Woah! Calm down. I know what you are thinking but no, not 343 Guilty Spark, the development studio that is a subsidiary of Microsoft, 343 Industries) uses a lot of trickery with the textures to get that network steady 60 FPS on the Xbox one. I can imagine that at some point even though you are the Master Chief someone somewhere will put up a fight as you wander about with the worlds of Halo 5, but you have seen adversity before and even when no one else was left standing you still managed to get the job done. I mean look at New Mombosa, you were what one of maybe a few dozen survivors that made it out and none of them survived to the next chapter. Think about it that one Marine with the bandage on his head just before Keyes called the “to War” command…where’s he?? Gone! That’s where. Dust in the wind! No longer present. His position has been eliminated, his services were no longer required, but you…you’re still here. So I say go for it, they basically took the only trace of love in your life and turned her bat&*^! crazy. But I digress.
Essentially the short and simple answer is you will need to start a blank project, setup your folder structure and begin importing the assets in an easily navigable arrangement. Open up Visual Studios and to start off in the editor click on File → New C++ Class and start setting up your global classes, from there you can begin setting up some of your higher level game logic/mechanics, followed by the too many to mention other objects, parameters, variables, states, etc. Over a long enough timeline any is possible, if you take your time and approach something with this amount of required effort in an organized and orderly fashion you can accomplish wonders in UE4.
I’m sure this isn’t the answer you were looking for (it may not even be the one you need), but it is at least a starting point for your journey ahead. Let me be the first to say good luck.
P.S. And may I also just say that I am a huge fan of your quiet but stern approach to every situation you have been forced to deal with and your level of discipline and fortitude is simply unheard of in the rest of the galaxy.