If this is not the correct path then enter the full path to match your installation. The default path is C:\Program Files\SEGA\Medieval II Total War\mods\kingdoms_grand_campaign_mod. If this is not you path, then type in the correct path when prompted for the install folder. The default path is C:\Program Files\SEGA\Medieval II Total War. They must be installed in the correct order for the new changes to work! Install patch 4.2 to the folder containing your Kingdoms.exe file. Then download and install KGCM patch 4.2 before you install KGCM patch 4.3. If M2TW Kingdoms was installed using the default path provided by SEGA then the install location will be C:\Program Files\SEGA\Medieval II Total War\mods\kingdoms_grand_campaign_mod It automatically installs the mod using this path.
The installer for v3.0 reads the system registry for the path to Kingdoms.exe. You will first need Kingdoms Grand Campaign Mod 3.0 installed. Before you begin the installation process, if you are using Vista or Windows 7, I strongly suggest that you read this tutorial and implement fix #3 to disable UAC for the M2TW folder only.