Just add the now cheap DVDRW drive to your build and boot that, install, etc.
Remember this question is also on the web so I'm giving my advice.
Currently working on my first build. I have the physical build complete and would like to load Windows 7 as I used an Intel - DH77DF Mini ITX LGA1155 Motherboard. I bought a key code from Kinquin. I would like to use my current Mac book pro using 10.6.8 OS X to create a USB boot drive.
What would be the best program to accomplish this on my Mac? Are there any pitfalls I should watch out for?
Thanks for your help in advance.