Atmega16 with Arduino IDE

Hi,
Came across this post about using Atmega16 with the Arduino IDE, with the 8MHz internal clock. Also, a separate ISP is used.

http://forum.arduino.cc/index.php?topic=172881.0

Was wondering about using an external clock, say 16MHz, and uploading sketches through the IDE serially. Can someone point out the modifications required to the methods detailed in the above post?