Hey, you know that's an excellent question, and if you get an answer, I'll be fascinated to read it.
The diseqc 'instruction set' for want of a better name has evolved over the years with the progression from 1.0 to 1.1 and more notably 1.2.
This has given rise to greater funtionality (as you are probably aware).
I think 1.0 just sent information to select one of four available 'positions' which is used to control switching between 4 different LNB's whereas 1.2 can do so much more. I don't have a clue what V2.0 has over 1.2.
A diseqc command can be anything from three to eight bytes in length, and an example would be (in Hexadecimal) E0 31 6E E1 38 (being 5 bytes) though I couldn't tell you what that means in English!
From what I understand, you can have different types of commands such as 'Goto angular position', 'Goto satellite position', 'Drive motor East/West (stepping)' and 'Store satellite position'.
I would like to know (like you) how this data is sent to the motor (or switch) i.e. how it is modulated, and onto which carrier. All I can say is that it's obviously a digital signal based on the nature of the data being sent.
STICK
P.S. Nice post.