Here's my first cut at C18 2.4 compatible code:
http://kevin.org/frc/ifi_frc_24_beta.zip
http://kevin.org/frc/ifi_frc_gyro_24_beta.zip (with ADC and gyro code)
Remember this is experimental code, so please do me (and everyone else who might use this code) a favor and let me know if you run into any bugs. Thanks.
-Kevin