clarity please regarding patching m2tw - unclear after much trawling

[mister_t]

Greetings, I wonder if anyone can shed a little light on my uncertainties regarding the patching of my installation of M2TW.
I have spent three evenings perusing multiple forums on this website, but still don't know how to proceed without risk...
My principle fear is that by running patches for a non-steam install on my C: drive, I will mess up my perfectly good Steam install.
The situation so far:
1) I have M2TW + Kingdoms + Third Age Total War running on a Steam installation on my C: drive under Program Files (x86). All is working perfectly. I want to leave this untouched.
2) I have ALSO installed the M2TW White Box retail version to my C: drive under C:\SEGA\Medieval II Total War. The vanilla v1.0 is working perfectly.
3) Now I need to patch the SECOND install to v1.2 and then 1.3 in order to finalize my dream of using this install to run the For King & Country mod, which is not suited for a Steam install.
4) I have downloaded the following files, hoping that they are the correct patches, and they currently reside in the Favourites\Downloads library:
miitw_update2_efigs_rc_final.exe
medieval_ii_update3_compatability_patch_efigs.rar

I am scared that unless I follow the correct procedure, the patching process might do bad things to my happily stable Steam M2TW setup, especially since Patch 1.2 is a .exe file.

Could some kind soul please lead me though the proper process, since I'm hesitant to pull the trigger on the .exe patch and am a bit unsure of the .rar patch.
Where do these files need to be situated before activating them, for instance?
I should say that I have a program called 7-Zip File Manager, which I'm guessing might be used for the .rar patch?

Any help in leading me by the nose through this process will be greatly, greatly appreciated. Especially since it took me FOUR failed transactions on Ebay to finally get the White Box game!!!
Many thanks,
Paul Turner

[Gigantus]

If the installers of the patches are executable files (as they should be) then it doesn't matter where you place them, they will install according to the registry entries on your machine. There are two things that can happen when you update:

1. It doesn't work because the installer detects the higher version of the steam installation and refuses to execute.
2. Everything goes as planned because the installer is looking for the specific registry entry of the disk version (different path in the registry from steam entry).

I am not familiar with the term 'white box' so I cannot comment on the upgrade files\installers you have. We do have an extensive list of patches here, just in case.