Get an account for Microsoft connect.
Step 1 .
Get your hands on a windows 10 install (so an iso for PC), i used en_windows_10_pro_technical_preview_10074_x64_dvd.iso (download it from http://windows.microsoft.com/en-us/windows/preview-iso )
Open the iso with 7zip (or any other program that can look into ISO's)
From the folder "sources" copy everything except the subfolders and the 2 biggest files (you can copy them ofcourse, but it will take less time if you skip them) to a folder on your PC. I put everything in C:\w10install . I am not sure which files are actually needed but just copying dism.exe and some dll's didnt work. So thats why I copy the whole directory.
I had to install Windows 10 ADK to get the file ffuprovider.dll which is not supplied in the latest Windows 10 ISO. Just install the ADK and then seach for ffuprovider.dll and copy this to the same location.
Copy the file Flash.ffu that you downloaded from the Microsoft site to this same folder. (this file is within Windows_IoT_Core_RPI2_BUILD.zip, that can be downloaded from https://connect.microsoft.com/windowsembeddedIoT/Downloads )
Start a command prompt (run as administrator)
Type the following commands:
And note the number of your SD card
dism.exe /Apply-Image /ImageFile:flash.ffu /ApplyDrive:\\.\PhysicalDriveN /SkipPlatformCheck
Where the N in PhysicalDriveN is the drive number from the previous step.
The image will now be written to the SD card
Thats it, now put the SD card in the Pi 2 and wait a while, it will boot up to Windows 10 IoT. The first boot will take quite some time, so have a bit of patience