Come at it from the other direction. Start in DPP and make your selection there. Batch convert to the folder containing the RAWs or to another folder if you wish to separate them and at the bottom of the batch dialog set it to open the tifs in LR. LR's Import dialog will open with the first tif. Wait until all have been converted and then click on the folder name in the left side panel and all your tifs (together with all the RAWs if they are in the same folder) will appear. Import from that whatever you want.
Well, DPP is a horrible selection tool. It's only strong point is that it's a marginally better raw conversion tool. Canon would really do everyone a great service by making a Lightroom ( and Aperture ) native Canon raw conversion plugin, instead of insisting on DPP on the Pro lineup. On location, I shoot tethered with Lightroom open for visualization.
Are you really so convinced that DPP does such a better job of raw conversion than Lightroom that you're willing to add that degree of complexity to your workflow?
DPP is marginally better for some food photoshoots, I did a side by size pixel peeping comparison on a few shoots, and DPP handles shadows on the 40D way better than Lightroom. Since the photos are for full size print on magazines and not web viewing, DPP gives that extra quality I'd like to provide. Still, for web viewing, Lightroom is enough, and for 99% of the time I just do it all inside of Lightroom. But there are those 1% where I want DPP to handle it, and I'd like it to be a bit less painful.
Again, wouldn't it be a great world if DPP just recognized Adobe's rating system, or, DPP came as a Lightroom raw conversion plugin or something? Meaning, DPP does the actual raw conversion on Canon cameras when you're in LR?