If you set a redpower sequencer to 300.00, it will sync to the world clock. One of each of the four outputs will be on at each different stage of the day.
1. Dawn-Noon, 2. Noon-Dusk, 3. Dusk-Midnight, 4. Midnight-Dawn
They should go in a clockwise order so all you have to do is hook up the dusk-midnight and midnight-dawn outputs to your lamps and it will turn them on.
P.S. Dawn is the point where monsters burn and dusk is when they spawn.