Let me see if I can break it down.
I tend to be bad at explaining things so, sorry if this is rough.
The idea is this: At the bottom whitespace (or somewhere on each page of the book) you would have a small printed row of randomly pre-rolled d6s faces. (or numbers if you wanted to make it even more compact).
Now, say you need to make a 2d6 roll?
You would take the book, and flip the pages stopping on a random one. Then you would look to the bottom and reading left to right, that would be your dice result.
Bottom of page page ten could have [6], [2], [3] in a bracket at the bottom.
- 6 and 2 would be the result.
Page twenty five could have [1], [4], [1], in its small bracket
- If you landed on it? 1 and 4 is your result.. and so on.
When you need to do 3d6, you just use the full random roll printed on the page from left to right.
The group could also agree to only use the first number printed, and flip three times.. or the last number and flip three times.. or even to alternate so on to make it even more random.
It wont be /perfectly/ random.. Still with only six possible results and dozens of pages, a random stop will usualy feel like fair enough of a chance to a player.
In an age of eletronics and everything its mostly uneccisary, but its sometimes handy to have the tool right in the book.