O.K... here it is..
Sorry I didn't chime in earlier to offer up the way. I wasn't here yet.
A very good, cool, high quality way to hook up your iPod to your Fit (Sport) is to use the Monster iCharger !

Notice : Sleek Black Color, Blends Nicely with Your Center Console, Monster Logo on Charger Lights Up for Cool LED Effect, in Red, Green or Yellow depending on Charging Status.
Plays well with :
Coiled Black Cable of iCharger Allows Placement of Audio Cable inside of Charger Cable, to Implement Clean, Single Cable Style Installation. Prevents Cable Strangulation Hazard ! !
See my avatar for a dark pic of the system in action. I'll post some pics later of the actual install setup. Just in case you can't make out what you see, that is a bottle of water lit up blue by LED illuminated cupholders, with the Monster iCharger glowing green in the upper left, with the iPod in the top middle area sitting in the pocket ahead of the cupholders.
The Monster iCharger hooks up to the dock at the bottom of the iPod, which gives a far superior sound output. What is also superb about this setup is that you do not have to adjust the volume on the iPod at all. The iCharger sets a constant volume output level which is unaffected by any ipod volume control changes on the iPod itself. This setup also virtually eliminates any potential noise to come out of the iPod audio sound.
The actual audio cable, (1/8" mini headphone male/male) which you do still need, hooks up to an input on the dock connector end of the charger cable, then you plug the other end of the audio cable into the aux audio input jack next to the charger socket. You can feed the audio cable through the charger cable, which is coiled, which makes for a "one cable" appearance to the total setup.
It's selling on amazon.com right now cheap, if you search for "iCharger" it should come right up, or just click on the link
here. Ignore the firewire type model. My background is audio, sound, recording, synthesizing, and I would highly recommend this Monster iPod accessory to add to your system for its quality, integration and simplicity. It is clean.
An added bonus is that the charger Monster symbol is LED lit, displaying a different color depending on the status. So now you can have another cool light in the center console of your Fit.
The only possible obstacle to using this right off, is if you have your iPod in a case that has alot of meat around the actual dock input of the ipod. With my case, I just carved away the excess to allow clearance of the dock connection, using an exacto knife. I've used my charger for a few years now, transferred it from my previous car to the Fit now.
You can make a nice clean installation, so that all you see is a cool LED lit charger sitting in the jack, and a short length of cable coming out with the dock connection cable to hook to your iPod. In my Fit, I've set it up with just the right amount of length to hook up to the ipod and sit it in the pocket in front of the cupholders, and tucked the rest of the cable away just above the center console. You can leave it hooked up all the time, since when the ignition is turned off, the power to that area is turned off.
I also set up an additional 12V input socket at the rear end of the center console to connect my cell phone charger, to be able to run both at the same time.
I hope this makes many happy iPod users. The Monster iCharger ! No substitutions, please ! !
If you have something different than an iPod, sorry to leave you out here. Peace !

e.b.