From Gentoo Linux Wiki

[edit] Installing

Ideally, you will need to create a LAMP server. You will need to install the following:

• An HTTPD
  • Apache
  • LightTPD
  • www-servers/cherokee
• PHP/mod_php Note: you need php with the xml use flag enabled.
• MySQL

It is a good idea to add vhosts either to /etc/make.conf or copy www-apps/ampache vhosts into /etc/portage/package.use. You may want to install MPD, as well as some of the associated USE flags. Finally, emerge www-apps/ampache.

Note: if you emerged ampache with vhosts flag, you need to run

webapp-config -I -h <host> -d ampache ampache <version>

first. To install it in the default host, replace <host> with "localhost".

[edit] Create the database

mysqladmin create ampache --user=root --password

Create a new user, "ampache":

mysql mysql -u root -p
mysql>CREATE USER ampache IDENTIFIED BY 'ampache_pass';
mysql> GRANT ALL PRIVILEGES ON ampache.* TO 'ampache';

[edit] Edit the config file

Make sure that the web_path variable is set:

####################
# Path Vars        #
####################

# The path to your ampache install
# Do not put a trailing / on this path
# For example if your site is located at http://localhost
# than you do not need to enter anything for the web_path
# if it is located at http://localhost/music you need to
# set web_path to /music
# DEFAULT: ""
web_path        = "/ampache"

Now you have to enter you database information:

###############################
# Session and Login Variables #
###############################

# Hostname of your Database
# DEFAULT: localhost
local_host = localhost

# Name of your ampache database
# DEFAULT: ampache
local_db = ampache

# Username for your ampache database
# DEFAULT: ""
local_username = ampache

# Password for your ampache database, this can not be blank
# this is a 'forced' security precaution, the default value
# will not work
# DEFAULT: ""
local_pass = ampache_pass

[edit] Test your install

Now just head over to http://localhost/ampache/, and follow the install procedures. All of the configuration should be done already for you, just continue to the last step, creating a user.