1. Remove the following files from the FastReport 3\Lib folder:
- frxrcClass.dcu
- frxrcDesgn.dcu
- frxrcInsp.dcu
- frxrcExports.dcu
  
2. Go folder with desired language and run mk.bat file. This will make 
.pas files from .frc files

3. Copy the *.pas files from desired folder to the FastReport 3\Lib folder.
  For FR3 Professional Edition:
- frxrcClass.pas -> FastReport 3\Source
- frxrcDesgn.pas -> FastReport 3\Source
- frxrcExports.pas -> FastReport 3\Source\ExportPack
- frxrcInsp.pas -> FastReport 3\Source

4. Recompile the FastReport packages (see install.txt file,
  section III or IV). Only frx*.dpk, frxe*.dpk packages need to
  be recompiled ('*' = your Delphi version).