Will a Rockbox'd iPod 5.5g work with an alarm clock iPod dock/car radio jack?

[No2iZod]

I hope you don't mind the newb question, esp. if it has already been asked (I searched and RTFM'd, but did not find), but because of the iPod Accessory Support thread I am now wondering: will a Rockbox'd 5.5g have any extended functionality on a Sony ICFCD3iP CD/iPod alarm clock radio and/or a Subaru stock head unit with iPod jack?  Will the 5.5g even be recognized in Rockbox mode, or would I have to switch to Apple FW, thereby necessitating the use of iTunes just to have content that the 5.5g will see when in Apple mode?

Background: I am thinking about getting a 5.5g primarily because of the ability to run Rockbox (I have stayed away from Apple specifically because of the "necessity" of running iTunes), and due to the fact that my wife just bought a Sony ICFCD3iP (because of the sound quality and CD player, not iPod-ability) to replace our dying RCA CD alarm clock, and because her car (Subaru) came with a proprietary iPod jack so that it can be controlled from the head unit.  The only reason I am selling my wife on getting an iPod is so that we can use it in the car and on the nightstand, but the only reason I want to get one is because of Rockbox.  In a nutshell, if I can't get a Rockbox'd 5.5g running on the Sony and/or Subaru radio in Rockbox mode, then I might as well go for a newer gen model since I will be forced to use iTunes anyway.  If that is the case, I may decide to hold off on getting an iPod altogether since I am a control freak and don't want to bow down before iTunes (hence my nick & pic).

TIA!

N2Z