A few weeks ago we posted an early guide to installing Windows 10 on ARM on a Lumia 950 XL. Now a more polished version of the guide is available, which is being updated as the process improves and more drivers are found.
Even this version, in its current state, however still leaves you with a device without WIFI, Cellular connectivity and even camera, so should really only be used on a secondary device you are not using day to day.
Adventurous and technically includes types can view the guide in full on OneDrive here.
Thanks, Jose for the tip.