Help on HP laserjet 4100

I would like to replace an old dot matrix printer with a new 4100tn laserjet printer. As you know laser jet does not impact on the paper, and I want to make three copies of my print job, I want each copy get printed in different color,therefore I will place 3 trays, one for each color.Here is the question: How can I print each copy from each tray, for example:
Copy # 1 from tray #1
Copy # 2 from tray # 2
Copy # 3 from tray # 3
Remember that the 3 copies will be from the same print job.
I will appreciate any input to this question.