This is in dev currently.
Once it is released you'll be able to do the following:
$ npm install zenircbot-api
And you'll be able to use it like so:
var ZenIRCBot = require('zenircbot-api').ZenIRCBot
var client = new ZenIRCBot(hostname='redis.server.location', port=6379)
client.send_privmsg(to='#channel', message='ohai')
Docs are availabe at: http://zenircbot.rtfd.org/