I am not a certified mechanic but I replaced the timing belt on my 03 odyssey a year ago without any problems so I will share with you my advice: 1) Buy a Haynes repair manual for 1999-2004 Odyssey. This is what I used and it has good step by step procedures with photos.
2) Get a crankshaft pully holding tool made by Powerbuilt to remove the crankshaft pully bolt. This will require a large breaker bar with all of your weight on it to break the bolt loose (about 400 ft-lbs) and another breaker bar to hold the pully.
3) Replace water pump and serpentine belts when doing the timing belt.
Good luck and let me know if you have any questions.