Set the RGB script to that (multi-line) python expression:
ret = """$pat = noise(10*$u,10*$v);
$out = ccurve($pat,
0.0, [{0},{1},{2}], 4,
0.5, [0.5, 0.0, 0.0], 4);
$out
""".format(thisNode.color1.get()[0],thisNode.color1.get()[1],thisNode.color1.get()[2])