Firmware Level Access

Is there any way to gain Firmware Level Access using RobotC?
if not is there any information available for using/creating a custom firmware for the Vex Microcontrollers?

I’m afraid not. You may be able to use MPLAB on the original VEX PIC.

Then is there anyway you would be able to expand RobotC to allow more of the ANSI C features to become available, like having the ability to pass methods as a parameter.