gentoo-overlay/sys-apps/linux-misc-apps/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
<maintainer type="person">
  <email>robbat2@gentoo.org</email>
</maintainer>
<use>
  <flag name="usbip">Include USB/IP binaries to replace <pkg>net-misc/usbip</pkg></flag>
</use>
</pkgmetadata>