autopilot: UAV command and control

Hi folks,
I am a German student working on a UAV project. I
bought a rotomotion IMU system a couple of months
ago.
This hardware is badly documented neigher on the
Internet nor on the delivered documentation cdrom, but
I managed to figure out how to read the gyro and PPM
data with a VB.Net engine, where the PPM data was
comming from my rc-receiver.
Has anybody ever worked with this IMU?
What I want to do is to design a computer guided modell
airplane which controlls its flightpath by itself using GPS
for position evaluation and the VB.NET engine (166Mhz
embedded low power PC).
How do I get to get this computer to control the servos
instead of the PPM data when I let the aircraft control
itself?
Does anybody know what $ERPNI does ?
Thank You?

Manuel