You cannot forward a hunt group directly, but this can be handled with a little trickery in the System Forward Paths, Remote Station Programming, and a Phantom Extension though.
Add a phantom extension and assign it a password, then setup a System Forward Path to the Hunt Group for all calls immediately and assign it to the phantom ext. Change all ring destinations of the hunt group to the Phantom Ext. To change it to ring somewhere else, all you need to do is Remote Station Programming of the phantom extension, which can be done manually (359+Phntm Ext+Password+355+8+destination #) or via a Station Speeddial assigned to a button. Manual Call Forward always overrides System Forward path.