Q: Camera Connection kit used as a USB port?

It likely won't work.  The USB connector that comes with the Camera Connection kit is designed to facilitate a connection between the iPad and a camera using a USB cable. 

I've tried using it for connections to other things, and it rarely works.

When the iPad first came out, it supplied much more power to the dock connector than it does now and it was much easier to connect things like USB keyboards and other USB devices. One of the first major iOS updates significantly changed that. It's a very low powered port.

Tgara is correct, the iPad one support a USB modem and not just because of the power issue. There's no way to install the drivers you'd need.

The camera connection kit can only be used to import photo/video files from a camera, SD card or USB flash drive. You can't import other types of files. You can't export any type of files using the camera connection kit.

Using The iPad Camera Connection Kit

http://support.apple.com/kb/HT4101

Secrets of the iPad Camera Connection Kit

http://howto.cnet.com/8301-11310_39-57401068-285/secrets-of-the-ipad-camera-conn ection-kit/

 Cheers, Tom