Check http://blog.jetbrains.com/idea/2014/03/intellij-idea-13-1-rc-introduces-sublime-text-style-multiple-selections/
Select next occurrence: Alt + J (Ctrl + G for Mac OS X)
Unselect next occurrence: Shift + Alt + J (Shift + Ctrl + G for Mac OS X)
Select all occurrences: Shift + Ctrl + Alt + J (Ctrl + Cmd + G for Mac OS X)
Remove all selections: Esc
Add/remove a selection: Alt + Shift + Mouse Click