I am about to complete my first round and will start a 16 week Oly training program immediately after. I plan to still do 3 hour long workouts per week as well as 2x s/b/r. You can definitely do P90X at the same time as you are tri training. You may want to replace the cardio elements of the program with s/b/r.
I have done a few rounds of P90X, and have had great results. I am now training for my first tri, and am only incorporating the strength training parts of the program. The cardio is replaced with my swim/bike/run.