I use the following bat file to do the renaming: (This was created by Black Angel One)
@ECHO OFF
ECHO Run Mass Effect 3 with Texmod?
SET /P X=(Y)es or (N)o?
IF /I "%X%"=="Y" goto :Yes
IF /I "%X%"=="N" goto :No
GOTO END
:Yes
ren "C:\Program Files (x86)\Origin Games\Mass Effect 3\Binaries\Win32\MassEffect3.exe" "MassEffect3_tmp.exe
ren "C:\Program Files (x86)\Origin Games\Mass Effect 3\Binaries\Win32\Texmod.exe" "MassEffect3.exe"
ECHO Files renamed! Please start now your Mass Effect 3 in Origin.
PAUSE
ren "C:\Program Files (x86)\Origin Games\Mass Effect 3\Binaries\Win32\MassEffect3.exe" "Texmod.exe"
ren "C:\Program Files (x86)\Origin Games\Mass Effect 3\Binaries\Win32\MassEffect3_tmp.exe" "MassEffect3.exe"
ECHO Filenames restored! Now you can start Mass Effect 3 with use of TexMod.
PAUSE
GOTO END
:No
"C:\Program Files (x86)\Origin Games\Mass Effect 3\Binaries\Win32\MassEffect3.exe"
:END
To create the bat file I copied the code above into Notepad (I prefer to use Notepad++), saved and then changed the .txt to .bat
Note: If your game is saved in a different file from "C:\Program Files (x86)\Origin Games\Mass Effect 3\Binaries\Win32" you'll want to change that information in the txt file.
I've attached a manual I created a that shows how to use the bat file.