Installing mPlayer

One of the most useful ports from the linux world is mPlayer. However, like most linux ports, it is difficult to install and configure.
Again on OS/2 World you find another interesting article by Robert Mauro. The article details how to install mPlayer in eCS, and how to use it as a plugin in SeaMonkey/Firefox to stream audio and video.
Given the number of different ports and packages you can find out there, I have often dreamed of a guide that let me install mPlayer without losing one or two hours trying to figure it out. Finally it is here!
Now if only someone could put together a WPI package... (hint, hint) :-)