I believe the max execution time warning (within the setup wizard) can be ignored by checking the "Ignore this test" checkbox. Simply ignore the test and see what happens.
As for 5 -> did you mean "five seconds"? That sounds like a very short execution-time setting. I'm not sure that all functionality of eZ publish will execute correctly within such a short time frame.
Yes, in fact, I've ignored and completed installation and yes newly, 5 means five seconds and is too short time, EzP don't work :-) I need to know the minimum time EzP need to work correctly, pls