Attention:
sys-boot/winusb has hit the main tree of gentoo, which is a better choice than winiso2usb. So this project is abandoned and will be deleted in 6 months.
winusb homepage: http://en.congelli.eu/prog_info_winusb.html
winusb ebuild: http://packages.gentoo.org/package/sys-boot/winusb?ts=2014-05-11T14:29:45Z