OK its as easy as 1-2-3 :
- select your "Conquest" folder in your CivilizationIII folder.
- right-click on it and COPY it
- Paste it on your desktop or anywhere else except the original folder.
- Name it "Conquest1.15"
- Once renamed, move it back into your "Civilization III" folder.
- Download the 1.22 patch and upgrade your Conquest the normal way.
Now you have both versions.
In order to switch from one to another :
- Select your "Conquest" file
- Rename it to "Conquest1.22"
- Select "Conquest1.15"
- Rename it "Conquest"
And vice versa
All save files and shortcuts will always point to the right folder thats the beauty of this trick...
The only issue with this is that once you have played one version you cant rename and play another one immediately : you have to first
restart the computer and them rename...
If anybody has a solution for that last issue, I'd love to know btw.
Good luck