Since ALSA is not installed on most Linux distroes, you need to compile it from source code. Download the files for driver, library, utilities (version 0.9.0rc7 currently), and install them sequentially.

After loading in the ALSA module, the mixer channels are by default muted. Run alsamixer to turn on relevent channels (press "m" key to unmute the highlighted channel, up/down arrow key to change value), and test with aplay some wavefiles in /usr/share/sounds/.

You can go on to configure KDE applications to work with ALSA, but as far as Lush is concerned, the work is done. The Lush interface for ALSA needs the libasound.so and associated header files, which by default should be in /usr/lib and /usr/include/alsa.

Start Lush, and type:

? (libload "alsa/alsa") 

More information about Alsa is available from: http://www.alsa-project.org/