What do you mean "update the embedded DNG preview..."? Have you actually processed a CO1 corrected image in the DNG format and been able to see your CO1 adjustments in LR or CS4?
I had the impression, that Nick misunderstood your All other image editors only see the original raw image
; he was thinking of the preview, while you were thinking of "applying the adjustments recorded by another raw processor".
In case this is so, you have to consider, that being able to read the adjustment parameters of another raw processor is the smaller issue. The real issue is, what to do with them. There is no standard of "contrast" or "fill light" etc., apart from more raw processor specific adjustments like "vibrance" in ACR or masked sharpening. For example the "Brightness" adjustment of ACR is not linear; but how it works exactly
is not described, nor would other raw processors apply every idea of Adobe equally - however, such an adjustment must work together with the others, like Recovery ad Fill; if the other raw processor does not reproduce the effect of one of those, the others become nonsensical.
Thus "passing" the adjustment parameters between raw processors is rather illusory.