Boot from USB on MacBook 1.1 (early 2007)
I was able to install Windows 8.1 by


Created a BOOTCAMP partition using the 10.6 Boot Camp tool (latest version available for 32-bit Macs)
Creating a Windows 7 USB stick on a PC using http://www.microsoft.com/en-us/download/windows-usb-dvd-download-tool
Install rEFInd http://www.rodsbooks.com/refind/
Start Windows Windows 7 installation
During disk/partiton select, choose to format the BOOTCAMP partition as NTFS (still, it refused to install)
Restart Windows installer, second time it would recognise partition as valid
Install Windows 7
Update to Windows 8


However, the Apple drivers for MacBook1,1 is pretty outdated unfortunately. Also, I would say that Windows 7 is a more appropriate OS for MacBook1,1.