its pretty easy... just go to the junk yard and cut out the radio harness of a 95-99 model maxima and either cut ur harness off or splice the wires like i did and use the pics from the link that ima post below to match up. ill post pics tomorrow of how it looks and the map i used... by the way it sounds gooooood!!!!!!!! also I've read that there a male and female harness you can buy so you dont have to do all of that.
95-99 radio harness pin out
http://carstereohelp.net/wireharness_Nissan2.htm
our radio harness pin out
http://carstereohelp.net/wireharness_Nissan1.htm