If you ever used IDA to analyze embedded stuff, you would immediately notice its pc-centric nature. While any embedded SDK targets specific devices with real-world part numbers, IDA just provides you with a universal analysis framework. You are supposed to know how the device works, its idiosyncrasies, programming model, memory organization, and all other practical stuff. If there is an automatic way to determine the entry point or interrupt vectors, IDA will use it but in general you will have to find out the correct parameters yourself.
The following tutorial fills the gap for C166 (and explains many other things!):
http://andywhittaker.com/ECU/DisassemblingaBoschME755/tabid/96/Default.aspx
Thanks, Andy!