AsteriskNOW 1.7 option 4 gives you the most convenient way to start up an asterisk server with the necessary libraries and modules loaded. It shall save you a lot time to compile and make them. For instance, the codecs G729 and G723 can be implemented by copying the codec DIRECTLY to the /usr/lib/asterisk/module directory.
iLBC can also be directly copied to /usr/lib/asterisk/module directory too. However, the speex.so could not. Investigation has been made to see if there any means to fix it.