Install Windows 7 via USB?

I have a 15" last gen macbook pro I removed the DVD drive to add an SSD, effectively having two storage drives. However I'd like to install Windows 7 on one of my drives, without picking up an external DVD drive is there a solution to install it? I tried using the Windows 7 -> USB tool that microsoft provides, but the system wont boot off it (when holding control as I load the machine).

Does anyone know how I can install Windows 7? Can I add a partition to one of my drives, "Restore" the ISO to the partition and boot off it?

Thanks, and merry christmas