Line 1 is 1 and 2 and Line 2 is 3 and 4. If you want it wired for 2 lines, connect red and green to 1 and 2 and move the yellow and black from 1 and 2 to 3 and 4.
If you want it to be wired as a single line set, bypassing the key, you can just connect the line to L1 and L2 on the terminal strip. As with all 302s, connect the red ringer wire to L1, the black ringer wire to K, the slate condenser wire to K, and the yellow condenser wire to L2.
You can also hook the line to L1 and L2 and the red ringer wire to 3 and the yellow condenser wire to 4. (The black ringer wire and slate condenser wire on K). Then you will have dial tone regardless of which way the key is turned, and the key can be used to turn the ringer on and off like a 305 set.