the best way to get help in a lisp is asking in the Visual LISP, AutoLISP and General Customization forum
Perhaps something like:
(defun c:test () (vl-load-com) (vla-sendcommand (vla-get-activedocument (vlax-get-acad-object)) "IEMBED\r") (princ) );; test
hope that helps
even in the other forum you have to provide more elements, just
"I tried your lisp but it did not work"
is not enough!
what did you got in the command line?
Unknown command "IEMBED". Press F1 for help.
or something else?
It is difficult to help without further details...