Form Data Submission Into Custom EE Table(s)

How do I submit form data from a web page (not the EE control panel) into a table that I created in my EE database? It is my understanding that SAEF and SafeCracker will put ONLY put data into a specified EE Channel (therefore, the exp_channel_data table).

Also, I would like to use EE’s out of the box authentication to only allow certain users (usergroups) to access and submit the form.

This was easy for me using strictly CI with other web-apps I have built.

Basically, when someone points to a specific url, I can see how the next action will be processed by either EE or CI, but not both. So I as you can tell, I do not have my head around the approach, and am still trying to apply CI MVC standards, instead of thinking like EE. This extension is not quite clear to me, I have seen other threads discussing module development, is building a custom module recommended for this situation? (Then talking to the custom module in the EE templates.)

I also realize that EE2 runs on CI2 so saying processed by EE vs. processed by CI can be confusing, but I think the question is clear enough.

The reason for this is more normalization of certain data that will take advantage of mySQL indexing when tens or hundreds of thousands of records will be handled by the database. Creating another EE channel will not work here. The EE database structure and logic are quite different from what I am accustomed to using, in order to give EE the flexibility that it has!

I would prefer to use EE’s core and any existing third party stuff. Any suggestions?

Perhaps an overview of the sequence of events that need to take place would help to get the ball rolling. I would also be interested in paying a consultant to help walk me through this if need be. Any recommendations?

Related threads/resources that I found:

Integrating a CI app with EE2 Using same CodeIgniter folder for both EE and CI projects? EE Noob: Extending Channel module to add custom functionality? Using EE with an existing CI application Harnessing the Power of CodeIgniter in ExpressionEngine 2.0

I am using:

CodeIgniter v2.0.0 ExpressionEngine v2.1.3

Here is a bit more of my background to help phrase the context of your responses:

I have a lower-mid level understanding of PHP, OOP, the CI framework, and concept of front controllers. I have read and watched the Ryan Irelan / Mijingo, Nettuts and Michael Boyink books and video tutorials, been through much of the EE and CI userguides and PHP manual when needed, so I am familiar with some of the logic involved. I have written my own authentication library for CI, but would rather use EE’s authentication.

Thanks for your help!