there's a WIP PR I have open that adds config file support to `nsqd`, `nsqlookupd`, and `nsqadmin`.  It's probably going to impact your PR here, so it might be a good idea to rebase this branch off of that one (although I haven't gotten to `nsqlookupd`, yet).

Perhaps just poke around and take note of the changes I'm making there.  More specifically, I think `nsqlookupd` will get an "options" struct like `nsqd` has.