Exactly the same way.
for (int i = 0; i < NUM_LEDS; i++){
int index = (i + offset) % NUM_LEDS;
if (i < (NUM_LEDS/2)) {
leds[index] = CRGB( round (170 + (i * 0.533333)), 0, round (20 + (i * 0.533333)));
} else {
leds[index] = CRGB( round (330 - (i * 0.533333)), 0, round (180 - (i * 0.533333)));
}
}