As far as I know (and I know this probably isn't the answer you wanted, but), the HDV 1080i60 codec is an "edit-only" codec that comes with Final Cut Pro. As such, it may not be available anywhere as something which can be downloaded independently so that QuickTime can use it; and, moreover, as an edit-only codec it's not really made for playback... and so one may not be able to utilize it in QuickTime even if one had a copy.
All that said, your question wasn't really whether or how to make it work but, rather, where to find it. Since it's part of the Final Cut Pro suite, I'd advise finding someone with that software; and if you think you'll know what to do with it when and if you could just get your hands on the codec on, for example, a CD or something, then see if a Final Cut Pro owner will offload the codec onto CD for you (or upload it to a web site and let you download it or something). You might also check the torrent sites... though, invariably, anything you get there would likely be, categorically, illegal... so I cannot and will not officially recommend it here (though I just looked at three of them and found nothing, so it's all moot, I guess).
Converting whatever it is you wish to play in QuickTime into a format which QuickTime may more easily understand would be the approach I'd take... perhaps using something like the VLC player, for example; or by using one of the many free media file converter utilities available out there.
