Sending Combination KeyStrokes to Application. ALT + Key

[Alegendxx]

(Working with MFC)

CWndObject.PostMessage(WM_KEYDOWN, 13) ;

that line of code sends the return carriage to the Window.
replacing 13 with any other character code sends that character to the Window.

I want to sent the simultaneous key press of ALT + w OR ALT + any other key.
How can I send the Key press of ALT and a character at the same time, to another window? without doing them one at a time.

Thanks