TeX Live and MacTeX ⇒ Dynamic updating TexLive

[curiouslearn]

In my excitement in the previous post I forgot to ask about dynamic updating in TexLive. Stefan, I read on your blog that TexLive is capable of dynamically updating the packages. Does dynamic updating mean that one can have packages installed from the command line just with a command install package name or does it mean that TexLive automatically downloads required package at the compile time (just the way MikTex does). If the latter, can someone help me how I can set that up.

Thanks very much.