ya sure. i always test read the pulse on the scope before connecting. 
actually i still dont really understand something. if you OR all the pulses, how will the microP be able to pick up the signal? since all 3 falls under 1 signal.
i read the 3 channels on the oscilloscope. the 1st 2 actually overlaps.. the 3rd pulse is somewhere in btween the other 2.
regarding the multiplexer. i had to control the channel (OUT) by pulsing 3 pins, a combination of either HIs or LOWs to get the pins i want. so basically i did that 3 times in a loop to get the 3 pulses.
is that the correct way to do?