It's actually 5v that runs the LEDs. You could rig up some type of resitor network with large resistors. That is what I was implying with the reisitors in place of one of the LED leads. I'm sure exactly what you are saying so here are a couple of drawings, one correct and one incorrect.
Correct
+---/\/\/----|>|------+
| |
+5v -------+---/\/\/----|>|------+----- GND
| |
+---/\/\/----|>|------+
| |
+---/\/\/----|>|------+
Incorrect
+---/\/\/---+---|>|------+
| | |
+5v -------+---/\/\/---+---|>|------+----- GND
| | |
+---/\/\/---+---|>|------+
| | |
+---/\/\/---+---|>|------+
On the empeg one side is replaced with the microcontroller, offhand I'm not sure which one.