Let me understand this correctly.
You have a LX accord and you want to use the Navi dash piece in a LX accord to fit the DD HU? If that's so, I don't think it would work or it would have been done by now, but hey you never know. I searched just for the front piece and I couldn't just find the front bezel by itself. I think the HU is integrated with the bezel, I am going to remove mine for some wiring I have to do this weekend. I will see if it's separate or integrated.
Another option is to buy the OEM audio attachment that goes in the lower pocket and use that. I believe it's plug and play if I remember correctly.