Well from what i can tell, (by using IDA decompiler) the bdmod.exe and bdmod.dll dont contain the code to actually make/create the paz files including new files like he does. Because the reason he sends the meta file with his downloadable mods is because he adds his meta to the game meta... And how he created his new meta.. is something we dont get to see. So the/his software to pack/repack meta and paz file we just dont have.
We only have the programs needed to add the meta he created to the main meta (bdmod.exe and dll). Smart way to not give away the secrets :)