The book doesn't have any special rules for how it should be set up and played; you only get one general, because you only have one full, 24AP multiple, and there's no additional PIPs. So strictly your PIPs have to stretch further, encouraging more reliance on group moves.
I know that one of the games played on Thursday used a slightly wider board - 3000p wide rather than 2400p. I played my game on a normal 2400p square board, and it didn't seem too cramped. In some ways it encouraged the use of a second line of troops - that great bugbear of many wargamers; a reserve. A large Hordes based army may find things tight, though, especially if they have a Stronghold too.
One thing we did do was allow a the general's element (or group) a free movement PIP, as with the CinC in a big battle. This certainly helped me, with a Magician general, especially as my early PIP rolls were abysmal.
So, have you played 36AP HOTT? What changes or additions did you put in place?