The Install option is controlled by a inffile File TYPE entry in the Classes key at HKEY_LOCAL_MACHINE\Software\Classes\inffile

Here is a Save Subtree As:

<b>Key Name:          SOFTWARE\Classes\inffile\shell
Class Name:        <NO CLASS>
 
Key Name:          SOFTWARE\Classes\inffile\shell\Install
Class Name:        <NO CLASS>
  Name:            <NO NAME>
  Type:            REG_SZ
  Data:            &Install
 
Key Name:          SOFTWARE\Classes\inffile\shell\Install\command
Class Name:        <NO CLASS>
  Name:            <NO NAME>
  Type:            REG_EXPAND_SZ
  Data:            %SystemRoot%\System32\rundll32.exe setupapi,InstallHinfSection DefaultInstall 132 %1</b>