Oh I know you can set the path for each of the software Runtimes you have, be it DS, Poser, Carrara, Bryce, etc., I just get very particular about parts of a set, like Materials and such, as I don't necessarily want them in the Materials Library. Usually that's where I put them, but sometimes I prefer to have the Materials as a subfolder in the appropriate Character/Prop's folder. I don't think you can get that specific as far as installing with DIM. It basically will let you set up separate Runtimes, but not allow you to setup specific destinations for "parts" of a product's package.
I could be wrong, but never saw that while beta testing it, so there may have been more advanced changes to DIM's installation in the past couple of years I'm not aware of.