There is no configuration file for the firmware. Use modifiable options are set with several #define statements in the main file (ArduIMU.pde). There are also #define statements which are not intended to be user modifiable options, so only change the parameters shown below.
//OUTPUTMODE=1 will print the corrected data, 0 will print uncorrected data of the gyros (with drift), 2 will print accelerometer only data
#define OUTPUTMODE 2
#define PRINT_ANALOGS 1 //Will print the analog raw data