The only option i've come across that works with D2B cars without COMAND
is the Dension GW500 D2B, which pretend to be a CD changer (although you can switch back to your CDC with a switch/power-cycle).
As the Audio-30 doesnt support CD text you dont see the track names etc, but you can still use the ipod controls themselves (unlike with the MB iPod kit for newer cars), but you have track control etc - you can see instructions at www.dension.com but remember to read them carefully to see how you use it with cars without CD text ...
With the Dension you can connect a USB stick full of music, or iPod, or aux-in RCA jacks. Its pretty easy to install, a 20mm hole cutter is useful to make a hole for the wires to go thru the supplied gromment. It charges the latest iPod & iPhones unlike some of the Merc iPod kits.
Comand Online now sells them, but they are quite hard to get hold of as the UK distributor seems not to hold any stock ... Theres more info about whats supported there ..
That is the correct dension link - but the one you need is D2B not MOST and the Audio-30 is a D2B unit that doesnt support CD-TEXT, thus dont expect the nice looking track menus as they show the latest head units only