From: rhasty@dialnet.net

#define INCL_WININPUT
#define INCL_DOSPROCESS
#include <OS2.H>
#include <stdio.h>
void main()
{
    BOOL rc;
    BYTE KeyState[256]; /* This is a 256 byte table   */
                        /* indexed by virtual key     */
                        /* value.                     */
                        /* For any virtual key, the   */
                        /* 0x80 bit is set if the key */
                        /* is down, and zero if it is */
                        /* up.  The 0x01 bit is set   */
                        /* if the key is toggled,     */
                        /* (pressed an odd number     */
                        /* of times), otherwise it is */
                        /* zero.                      */
    
    DosSetPriority( PRTYS_PROCESS, PRTYC_IDLETIME, 2,0);
    while(1)
    {
        rc=WinSetKeyboardStateTable(HWND_DESKTOP,
          /* the address of the second element is passed so that the */
          /* key number corresponds to the array index               */
                                 &KeyState,
                                 FALSE); /* get a copy of the keyboard */
                                         /* state.                     */
        if(rc==FALSE)
        {
            WinAlarm(HWND_DESKTOP, WA_ERROR);
            return;
        }
        KeyState[VK_NUMLOCK] |= 0x01;    /* set the NUMLOCK key to     */
                                         /* on state                   */
        rc=WinSetKeyboardStateTable(HWND_DESKTOP,
                                 &KeyState,
                                 TRUE); /* set a copy of the keyboard */
                                        /* state.                     */
        DosSleep(5000);
        if(rc==FALSE)
            puts("Error Setting copy");
    } // While 
} // main