I recall the truck having sand bags on one side to force the explosion in the direction of least resistance. For some reason, I was thinking he did use nitro methane --it's not THAT hard to get if you say it's used for racing fuel.
I do recall him using drums, wanna say they were the blue plastic ones, and the stuff has to be detonated with dynamite and that in turn with a blasting cap but I don't recall the details of that. So it was more like a truck full of barrels, kinda like in "Fight Club".
As for sequencing the detonation, it wouldn't be necessary nor would it do much in this case. The charges were all too close to one another and it would have been wiser, IMO, to wire them all parallel and blow them at once to ensure total detonation of the ANFO.
Physics and timing and then pulling it off in reality are different things, for instance, it's possible on paper to wire a charge such that it will compress sound waves and work like an EMP (I forget where I saw the drawings and such but I think it was when I was studying math). But to my knowledge it's never been done.