Wrap custom installer, that is installed during install/update cmd

[gossi]

When a package requires a custom installer, sth like this:

"require" : {
    "php" : ">=5.4",
    "keeko/composer-installer" : "*"
}

This custom installer will be installed during the install/update process. Yet, cannot be wrapped, because installManager form Composer is already passed to Installer and at the moment, I don't know of a way to get to the installer and update the install manager there.