Welcome to the forums Chris. I am a pilot as well though I do not have the eFlyBook, just a straight iLiad. I can understand your needs, I am not a developer so I cannot specifically state what you can do, though there are some very talented people here that might be able to help. There is a patch that can be applied to the firmware that will allow for "shell access" I do not know if something could be accomplished with that.
The other alternative would be to go to iRex directly with your request. They have a forum that has some of the actual iRex developers responding to posts. They might be able to assist you.
See
iRex Forums
Good Luck!