At the switches where you have 2 core and earth leave the black wires where they are and connect one red to L1 and the other to L2 on one of the switches, at the other end put the red wires in the switch controlling the other lights.
The 3 core and earth connect the same way at each switch (eg red to L1, Blue to L2, Yellow to COM), which it sounds like you have done already.
Adam
February 2010