per package permissions

Is it be possible to somehow interject per package permissions control (within a single index) in to the current devpi setup? or is the only way to do that via a development index per package? Even if it is a combo of both "auth_user" and "on_upload" hook that I would need to write...is it doable? If not, I'm curious what is perhaps the most number of indexes folks have used? I'm pretty sure I would be hitting in to the hundreds (but probably not thousands). Thanks, Kevin