Hey Guys,
Based on the guides by Virtualrepublic and Scrubs, I was able to achieve a fairly good result with Blender Cycles, importing an Ldraw model with the importer. (I had to modify the studs to create non-beveled versions, as I also had problems with the geometry there.) My next step is to try and reproduce some of the original catalog photos :D
(The render is not super high res, I don't have a fast enough machine at the moment..)