REM VBoxManage is not in PATH, but this is a good guess
IF EXIST %ProgramFiles%\Oracle\VirtualBox\VBoxManage.exe (
    SET PATH=%PATH%;%ProgramFiles%\Oracle\VirtualBox
    ECHO.
    ECHO %time% Found %ProgramFiles%\Oracle\VirtualBox\VBoxManage.exe
    ECHO.
    GOTO :vbm_found
)

ECHO.
ECHO %time% Searching %SystemDrive% for VBoxManage, this may take a while
ECHO.
FOR /r %SystemDrive% %%a IN (*) DO (
    IF "%%~nxa"=="VBoxManage.exe" (
        SET PATH=%PATH%;%%~dpa
        ECHO %time% Found %%~dpnxa
        GOTO :vbm_found
    )
)

ECHO.
ECHO %time% Cannot find VBoxManage.exe (part of VirtualBox) on %SystemDrive%.
ECHO %time% Program stops.
ECHO.
GOTO :terminate

:vbm_found

REM vim: set ai ts=4 sw=4 et ft=dosbatch: