Problem I am having is I can't seem to find out how to do an interrupt off a serial input to deliver the new patterns from the c# app to the cube? Anybody have example code of how to drive an interrupt off a serial line?
You don't need interrupts to read serial data. Just add a call to Serial.available() in loop. If Serial.available() returns a number of bytes greater than 0, read the available data. When it is enough, use the new data instead of the old data.