[eluser]Mischievous[/eluser]
Personally, nothing against any of the authors of plugins or components built for Codeigniter. Build your own, it will be easier to get it just the way you want... without having to modify someone else's code. User authentication class maybe takes a couple days to build out? The only component I would suggest is Modular Seperation.
Suggestion: Grab a copy of Codeigniter 2.0 from GitHub and then grab Philsturgions hack to modular seperation to port it to codeigniter 2. Then begin your work...
Setup your basics first... your gonna need a template engine etc... but I would suggest roughing out your database schema first. that will tell you how you need to build your models/classes and how the system needs to interact. Think about all the posssibilities and pre-plan pre-plan pre-plan.
Just my 2 cents
