These are really basic instructions, but they should help.
 
First, requirements:
 
1) PostgreSQL
2) Lighttpd (or Apache 2)
3) PHP:
    You need these modules: PDO, PDO PgSQL, Hash, Memcache, Tokenizer
    PEAR modules: Auth/OpenID
4) Memcached
 
To install the software, place it into a web directory, and then configure lighttpd
with the rewrite rules needed:
 
        server.document-root = "/web/pastebin.ca/htdocs"
        accesslog.filename = var.logdir + "/pastebin.ca-access.log"
        dir-listing.activate = "disable"
 
        url.rewrite = (
                "^/([0-9]+)([,'\".;]+)(\?.*)?" => "/$1$3",
                "^/([0-9]+)(\.html?)?$" => "/index.php?id=$1",
                "^/([0-9]+)(\.html?)?\?(.*)$" => "/index.php?id=$1&$3",
                "^/([A-Z][0-9a-zA-Z-]{5,8})([,'\".;]+)(\?.*)?" => "/$1$3",
                "^/([A-Z][0-9a-zA-Z-]{5,8})(\.html?)?$" => "/index.php?mask=$1",
                "^/([A-Z][0-9a-zA-Z-]{5,8})(\.html?)?\?(.*)$" => "/index.php?mask=$1&$3",
                "^/new(\.html?|\.php)?$" => "/index.php?a=n",
                "^/archives?([0-9]+)(\.html?)?$" => "/archives.php?page=$1",
                "^/tree([0-9]+)(\.html?|\.php)?$" => "/tree.php?tree=$1",
                "^/desc([0-9]+)(\.html?|\.php)?$" => "/tree.php?id=$1",
                "^/raw/([0-9]+)(\.html?|\.txt)?$" => "/raw.php/$1",
                "^/rss/(.*)$" => "/rss.php/$1",
                "^/download/(.*)$" => "/download.php/$1"
        )
        server.error-handler-404 = "/error404.php"
 
 
Configuration:
 
1) Copy localsettings.inc.php.sample to localsettings.inc.php in the htdocs/include/ directory
2) Customize these values to your server