How can you boot a proliant server from a USB flash drive?
Download and use the HP Drive Key Boot Utility, which can be found here - http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?swItem=MTX-UNITY-I23839&lang=en&cc=us&idx=1&mode=4&
It is pretty self explanatory after you install the utility but if you need further directions a complete walkthrough can be found here – http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00218060/c00218060.pdf