Ficedula and Qhimm already have released source code available for download. Qhimm's source is all the same as the versions he has available, but some of Ficedula's is behind his current releases. And, yeah, Ficedula's the only one who uses Delphi (and, IIRC, not all of it is Delphi 6, some of it is older.)
If you want to mess around with their source, just download, and, if you alter+distribute, credit them appropriately. Heck, just follow their terms (included *with* their source distributions in most cases.)