You can use a RF Modulator, some people have okay luck with them, some people say they are horrible. Other then that, you can't.
You truly should consider upgrading to a new model deck if your looking to use your ipod, there are a very many new or newer model h/u's out there that have ipod integration built into them now, it's almost becomeing a stanard option. I suggest you try to stay away from sony again though.