As mentioned earlier, I went back and read the entire World War Hulk event. Here is the order:
World War Hulk (optional)
[As usual, I'm skipping a lot of irrelevant tie-ins that do not contribute to the main narrative. Only Incredible Hulk v2 issues add something to the story. Also includes the X-Men tie-in which fits well because the whole point of this story is the Hulk's revenge on the Illuminati and Charles Xavier is part of that group so it fits perfectly.]
Incredible Hulk v2 #106
World War Hulk Prologue: World Breaker (1st story)
Incredible Hulk v2 #107 (p. 1-7)
World War Hulk #1 (p. 1-20)
Incredible Hulk v2 #107 (p. 8-12)
World War Hulk: X-Men #1-3
World War Hulk #1 (p. 21-end)
World War Hulk #2 (p. 1-35:3)
Incredible Hulk v2 #107 (p. 15-end)
Incredible Hulk v2 #109 (p. 1-2)
World War Hulk #2 (p. 36-end)
World War Hulk #3 (p. 1-24)
Incredible Hulk v2 #109 (p. 7:4-end)
Incredible Hulk v2 #110
World War Hulk #3 (p. 25-end)
World War Hulk #4-5
World War Hulk: Aftersmash
Next comes Fall of the Hulks and World War Hulks because I've realized that the X-Men are also part of that event.