Is it possible to add DPP to the workflow (manually or automatically) so that it gives a preferred starting image?
I've looked, but can't find a way of getting the DPP recipe 'baked' so that LR / ACR takes it as a starting point.
Is this possible?
Directly no, indirectly yes but not with the original raw file. Basically you'd have to do your raw editing in DPP if the results it produces are the one your most happy with. Then save out the TIFF file that DPP produces and Import that file into Lightroom either for cataloguing or further editing. If anything is to be gained from this I don't know as I'm perfectly happy with LR/ACR's rendition of raw files and have never tried it.