Adobe DNG / TIFF SDK | Handling Packed RAW formats

Does anybody know if the Adobe DNG / TIFF Spec has a way to handle packed RAW formats? 

That is RAW image data where the pixels are not contiguous in memory?

For example of a 12-bit RAW image with a packed format 2 pixels are spread across 3 bytes like this:

 AAAAAAAA BBBBBBBB BBBBAAAA 

Is there a way to specify using DNG tags that the pixels are stored this way and to have the DNG readers be able to unpack it? 

If this is not supported, I would really like to see Adobe adopt this.