I just wanted to bump this thread and first of all say "THANKS!" for providing the excellent information/tutorial.
I also wanted to pass along this link for DIY types who might want to make their OWN intervelometer. These links are (again) for Canon, so Pentax users (like me) will want to do something similar to the info in this thread to modify it for Pentax.
http://www.sporez.com/honeyjar/?p=347
A video made with the device:
http://www.sporez.com/honeyjar/?p=360
In the comments to the first link is another link to a similar homemade device designed to drive Canon Rebels:
http://ozastro.dyndns.org/avr_timer.html