FAT custom driver

I have run into major space problems with my web application. Currently using FS2. I need to serve up a Java Applet file from the rabbit system. This file is over 80kb in size and It simply does not fit, crashing out of the compile due to lack of space. So I am changing approach.

I see from digging around that there is facility to write a custom driver for the fat add on. I want to use a RCM 3000 core module on the prototyping board along with a custom connected SD card and I’d like to try to develop a driver to suit my setup rather than use the rabbit serail flash board.

Is there any documentation on how to approach writing a driver for the fat system?