very easy my friend..
There is a device available which can be plugged into Cigrette lighter. You insert a normal USB drive filled with MP3 songs. It will transmit the songs on your FM radio. So you can hear MP3 songs on your normal car deck with FM radio.
Its available in a very less price. From Dubai you can get it in around 160 DHm and some one was telling me it was available at illusions Jinnah Super at 2900 Rs.
I hope it will work for you.
Regards