On my dual-drive MacBook Pro I have remapped the eject key to F13 using Karabiner and NoEjectDelay. The eject key has been assigned as the hotkey for a guake-style visor terminal using iTerm2. Having its own hotkey precludes the need for an icon, so I prefer to hide the iTerm dock icon.
####To hide the dock icon of iTerm2 on Mac OS X:
/usr/libexec/PlistBuddy -c 'Add :LSUIElement bool true' /Applications/iTerm.app/Contents/Info.plist
####To undo the above:
/usr/libexec/PlistBuddy -c 'Delete :LSUIElement' /Applications/iTerm.app/Contents/Info.plist
####Disable animation of hotkey window on iTerm2:
defaults write com.googlecode.iterm2 HotkeyTermAnimationDuration -float 0.00001
######tested with iTerm 2.0.0.20150412 on Apple MacBook Pro (Late 2011) running OS X 10.10.3