is there a spot on the factory head unit on a 2002 for a rca to go into

If I am not mistaken , you need a special cable and use the cd port. Look for autotoys.com and/or search for a cable call AUX AUD MP3 SYMP. It cost around $100.

About a week ago someone posted a link on here for an auxiliary input adapter (http://www.discountcarstereo.com/detail.aspx?ID=399) --- this part will allow Left and Right audio into the radio--- we used it to add an ipod mini to A4.
Good luck.