Get a radio that has the aux input or get someone to rig one to the radio. A radio/electronic repair guy should be able to do it.

To install the factory Infinity satellite radio, your car stereo needs to have a SAT button if older 2004 and under your vehicle will need to have a CD CHG button, you need the correct aux interface, to use any portable satellite radio, you can find them here
http://www.oemautosound.com/c-37-nissan-auxiliary-adapter.aspx

good luck