Building a bootable USB for HP's Service Pack for Proliant ISO is accomplished by using HP's USB Key Utility version 2.0 or beyond.
To download the Service Pack for Proliant, use this link for the 2015.06.0 edition or use search. Currently There's an "Obtain Software" link which requires a valid support login. Directions for building a bootable usb over 4 GB using HP's USB Key Utility for Windows are including in the HP Service Pack for Proliant Quick Start Guide, which oddly isn't listed on the download page and had to search for it separately.
The HP USB Key Utility is available for download, may need to search and then check Revision History to locate version 2.0 or beyond. From what I understand earlier versions do not support x64 bit and/or 4 GB+.
