You should be able to use Hubot with Grove as it provides IRC interface. We have few users already using it.
Assuming you'll have to create an entirely new Grove account for each bot you want to add, though?
That's fairly typical though.
Hubot does provide the irc-interface but then github itself doesn't provide a hubot hook. So you're pretty much stuck at the same place. Github itself does provide an IRC hook but that does not work since it can't authenticate with nickserv, it only allows for server and room passwords.