Perhaps something like;
Code:
If Counter < 11 THEN

  If Counter // 2 = 0 THEN
    LED1 = 1
  ELSE
    LED0 = 0
  ENDIF

ELSE

  IF Counter // 2 = 0 THEN
    LED2 = 1
  ELSE
    LED2 = 0
  ENDIF

ENDIF
/Henrik.