You can send any keystroke to a window once you found the handle of
the window, as you did.
Use the PostMessage() API function to send WM_CHAR messages.

For example:

DECLARE INTEGER FindWindow IN WIN32API INTEGER, STRING
DECLARE INTEGER PostMessage IN WIN32API INTEGER, INTEGER, INTEGER, INTEGER
WM_CHAR = 258
hw = FindWindow(0, "Oracle Applications - PROD #1")

str = "FC.EN.CD" 
FOR i=1 TO LEN(str)
       ? PostMessage(hw, WM_CHAR, ASC(SUBSTR(str,i,1)), 0)
ENDFOR