As far as I know, you can't send IR info in LIRC format. The 2nd link you provided has a Flags sections that shows the IR protocols LIRC understands. You'd need to write (or find) a sketch that can output an IR signal that conforms to one or more of these protocols. Which one(s) should you use? That depends on the various devices you want to control. You may find that one device understands RC5 while another uses SIRC (Sony stuff mostly) or then again they might use an entirely different protocol.
The 2nd post in the forum link you provided will take you to a discussion (and sketches!) of the Sony and RC5 (also known as Manchester encoding I believe) protocols. You'll find both receive and transmit stuff there. I'm using the Sony receive code I found there to help me add IR capability to a wired Creative Megaworks 250D remote