Starting in 2008 supra put a direct iPod connector by the stereo. It is a relatively inexpensive part that plugs in where the cd changer plugs in. You can use a 3.5 mm cord to connect your iPod. Install takes about 5 minutes.
Get a harmon kardon drive and play systems... get one of the old ones and you can find them online for $35 ish...... Well worth the investment... That way you can charge and operate it just like you operate your Ipod... The Kenwood interface is not nearly as user friendly.
I have one of these in my 22ssv. It plugs into the back of the head unit in place of the 3.5mm jack that supra put in their boats this year. It works great, you can control your iPod from the head unit and the driver and transom remote.
I think I'm lucky because I've both, the IP500 and the Harman kardon. I love the Harman kardon,But in the radio instruction manual there isn't a connection for the harman kardon, only if you have the antenne adaptor.
I have the IP500 Kenwood adapter in my Supra 22SSV (2007) and it works fine. Remote stereo adapter controls the ipod as well as the head unit. I haven't spent a lot of time figuring it out yet, just installed it this summer. Easy 60 second install.