Don't think so.
Sideloading is only possible when you have access to the full settings menu and can access the checkbox "Allow non-market applications" or something like that.
While standard Android phones have access to that setting without root, the NC uses a customized shell that doesn't give the user access to those settings. Only way I know of is to root and then get access to that setting, but then again, if you've rooted, then you have market access and can just download it.