This is a stupid method but enough for 99% person

create a text file

paste
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\msnmsgr.exe" /v debugger /t reg_sz /d debugfile.exe /f
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\WLinstaller.exe" /v debugger /t reg_sz /d debugfile.exe /f

and save as block.bat and run it

to remove it
create another file
reg delete "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\msnmsgr.exe" /f
reg delete "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\WLinstaller.exe" /f
and save as remove.bat and run it

please note that msnmsgr.exe and WLinstaller.exe are the default exe name, once user change the names, the installer/programme still be ran again!