Trying to install Windows 10 on early 2008 MBP without using the BootCamp Assistant I have an early 2008 MBP, where I installed El Capitan. However I would like to split my HD and install Win10 as well. Since there is no direct support, it is quite difficult. 
I find this question "How do I get Windows 10 installed on my macbook pro (late 2008)" here with a logical answer which was "How to install Windows without using the BootCamp Assistant." 
My issue is when I want to bless my HD in Terminal, I get the following error message "Could not set boot device property: 0xe00002bc" and thus the rest of the instructions do not work.

Any suggestions, recommendations, idea how to solve it? 

I already made a brand new OSX install, but the error is still the same. 

Any help is appreciated.
Just a thought, but can you install Win 7 using the bootcamp that is designed for your system and then once installed upgrade to Win 10?

Note that the Windows 10 bootcamp drivers will not likely support your hardware but I have had some moderate success updating bootcamp drivers on Windows installations from within Windows by identifying any unsupported hardware by their hardware ID (in device manager) and then downloading the driver directly from the manufacturer.