Originally Posted by: BigDog_Jimis there some magic forumulea that can help me to figure out second guitar parts?...
How can I quickly decipher these subtitute chords? If there is no easy answer for the theory illiterate where should I start?

The solution is to learn to play any given chord in multiple locations on the guitar fretboard. Different strings, different positions will result in different sounds. So, both (or all) guitars are playing the same C major chord, but one might be playing it as a simple open position chord, but the other part might be as a triad inversion higher on the guitar.

The fundamental idea here, is that any place on the guitar you can find the notes C, E & G is a C major chord. And there are lots & lots of places to do this. :)

These tutorial will teach you the basic concepts of triads & inversions:

http://www.guitartricks.com/tutorial.php?input=148
http://www.guitartricks.com/tutorial.php?input=824

These tutorial will teach how to practice & use them:

http://www.guitartricks.com/tutorial.php?input=730
http://www.guitartricks.com/tutorial.php?input=731
http://www.guitartricks.com/tutorial.php?input=733
http://www.guitartricks.com/tutorial.php?input=734

Hope this helps. Have fun!