After getting all the required files, it's time to get the level editor ready. But first :
Protecting the Extracted Files
This part isn't required, but it's recommended as it will protect the files you've extracted earlier on from accidental edits or deletions.
To do this, download this script (Windows only) and place it in the same folder as the extracted files.
Right-click the script and choose Run as Admin (input the admin password if required). You will now be asked to input the folder name.
After typing the folder name, press Enter to apply the protection. When the script has finished its job, press any button to close the window.
Downloading and Running Reggie
You now have everything needed to run the level editor! Download it at this link. If you're on OS X or Linux, you will have to use a software such as WINE or run the source code version. Instructions for the latter are here.
Once you're done downloading Reggie, extract it and run reggie.exe.
You will be presented with this :
You will have to point Reggie to the Stage Folder you extracted before. Make sure you point to "Stage", and not the entire dump folder, or the program will give an error. Press Select Folder to confirm.
If everything goes well, you will see the original game's World 1-1 load in the editor !
Feel now free to poke with Reggie. Don't forget to have a look at the interface guide to get some more information on how the program works. If you're looking to play any of your products, look here instead.