yes there is jo. You use the yellow and black wires of a standard 4 strand wire for the second line. Red and green is used for the first line. Do you have the second line already hooked up from the phone company? They need to do this first.
If so then out at the outdoor phone connection box, you will hook up the yellow and black of the wire going into the house to the red and green of the second line jack. The red and green wire of the wire going into the house should already be hooked up to the red and green on the jack for the first line already there.
Then buy a triplex 2 line plug adapter for a few bucks from walmart. It has 3 outlets, line 1 for your phone, line 2 for your modem, and then line 1&2 for a two line phone or to use line 1 again on the middle two wires. Install it by the computer.