I have 267GB of unallocated space that I want to install onto. (Installing eOS, but the installer is the same). I was going to use the option for a custom install, but didn't know where to put the boot loader. I use Windows7. I also wanted to know if I should create a new partition from Windows. Or if I can do that from the installer. Thanks!
Since you have said that the installer is the same, I am just giving instructions based on my experience from installing Ubuntu.
Under the section
You can create the new partition from the installer itself.