I've developed some quick GUIs for manipulating the terrain data. They both go in the scripts folder.
1. Designator GUI - Download
This can perform the same functions as designator.py. Move the in-game cursor to the tile you want to clone and press 'Get' in the third row, next to the boxes for tile type. Move the cursor to the top-left coordinates to clone to, and press 'Get' in the first row. Move it to the bottom-right corner and do the same to the second row. Then click 'Set tiles' and it will do it. You can type a name into the lower box and press Save to save the tile info to a file (tileinfo.db). Press Load to load the info with the name in the box. The action buttons off to the right will perform the labeled actions to the tile info - they are not very useful right now.
2. Designation Flag GUI - Download
This program will allow you to easily edit the 2nd number of a tile. Press Load to load the tile under the cursor into the program. Then you can edit the checkboxes and press Save to save it to the tile. Modifying the checkboxes will change the value in the entry field, which is the hex representation of the binary data in the checkboxes. If you modify the hex value, you must press Update to update the checkboxes. The boxes are labeled with an abbreviation of what they do; you can see the full details of what I've found at my user page.
Edit: Messed up links
[ February 17, 2008: Message edited by: Valdemar ]