Alrighty, Just got this working on the latest version for myself (1.1.49) on steam.
Also made an account just for this, so you're welcome....
What you will require:
HxD
Pawelzwroneks Factorio savegame .datX unpacker/packer
A Factorio save
Step 1: Getting the tools
Download HxD from above, and open up Pawelzwroneks GitHub page, go to %appdata%/Factorio/saves (or wherever your saves are located) and make a backup of the world. Mine is called caydog.zip, so I copied caydog.zip to caydog_BACKUP.zip. Move the original zip to your desktop or somewhere without clutter, I suggest making your own folder. Simply unzip the world, you should have a folder with the name of your world inside, then inside that, heaps of level.datXX files depending on how long you've played.
Step 2: Unpacking
Heres the annoying step, you're gonna want to go back to the Github page, click the "Choose File" button after "Unpack", and select your level.dat0 file. This will download a new file with a randomly generated name. Rename the file that was downloaded to something like "level.dat0u" for ease. Now do this with every level.datXX file in that directory. Personally, after 30Hrs of in-game, I had 20 level.datXX's all up (level.dat0->level.dat19). You should now have the same amount of level.datXXu's as level.datXX's in the original folder.
Step 3: HxD
Open up HxD, then drag all of the level.datXXu files into the main screen, it should open them all up in different tabs. You're going to want to find (CTRL+F) for a Text-string called "command-ran". As long as you haven't been cheating this whole entire time, there should only be a few files that return results. For ANY file that managed to find the string "command-ran", you want to move it to a separate directory, these are the files we're going to be patching. Delete all of the level.datXXu files that didn't find the string, theyre no help to us. Personally, I had one file (level.dat18u), which made it easier, but you may have more.
Step 4: Patching
Now that you have all of the files in a directory, your want to open them all up in HxD again, then do a Hex-values search for "FF FF 00 01 00". Now on the left side, you need to change it from "FF FF 00 01 00" to "FF FF 00 00 00", by replacing the 1 with a 0. Rinse and repeat for all the files. Click File > Save All, the close HxD. In the directory, you should see all of the level.datXXu files, as well as level.datXXu.bak files, just delete the .bak files, they're not needed.
Step 5: Re-packing
Head on back to Pawelzwroneks GitHub page, then next to Pack, click Choose file, you're gonna want to choose all of those level.datXXu files that we just edited, you'll have to change the .bin at the bottom of the file chooser to all files to see them. Do the rename thing again, this time removing the trailing u character. For instance if you uploaded a level.dat19u, you should rename the downloaded file to level.dat19. Once you have all of these re-downloaded, jump to the next step.
Step 6: Finalizing
Well this is exciting, final step!
Take all of those downloaded files, and find where you extracted your save to for the first time, where you originally got the level.datXX files from. You're just going to cut and paste the downloaded ones into there. Make sure to replace (obviously) when prompted. Then go up a directory, select your world name, zip it any way you want (I use 7-zip, so simply right click the folder > 7-Zip > Add to archive), and move it back to your factorio saves location. Double check by opening up the zip file, that it contains a single folder, with your world name, and multiple files and directories inside that. Launch factorio, and see if you can open your world! If so congratulations, you got achievements back, now stop cheating!
Step 7: If corrupt
If it says something about the world being corrupt, or if it just doesn't open, go back, re-read this tutorial, try it again. If it doesnt work a second time, then maybe its been patched idk. To revert your world back to normal, simply delete the .zip you made, then rename your *_ BACKUP.zip file back to normal.
Hope this helps!