Requirements 

Unlike other tools, you don't need to install a database or require an account to process your stats.
Scripts can be run from your own directory as a user (if you can't install the script in the cgi area). But some tools will not be available as they require cgi, as the web administration interface which allow you to run the stats remotely or build your configuration files from forms.
Even logfiles are not required as you could insert a javascript tag in your html pages which will produce logfiles for you.
All you need is Perl !

- Mandatory software

In order to use W3Perl, you just need to install Perl. Linux/Unix/MacOS have Perl already installed but Windows user should get it from Strawberry Perl or ActivePerl (the latest will also configure your IIS settings)

- Plug-in

Different plug-in are available :

  • Geo::IP or Geo::IPfree : To map IP with country code without querying DNS
  • Mime::Lite : To receive email reports
  • DBI : To extract page's title from SPIP database
  • Htmldoc : To generate PDF reports
  • GeoLiteCity : To get cities stats

- CPU/RAM

W3Perl is memory hungry. More RAM you will have, the better it is. Parsing a 1 Gb logfile will require 100 Mb of RAM with the default level of precision. If you switch to the highest level, the amount of RAM required is around the same size of your logfile so use it only for short period of time or with low website.

It's safer to run W3Perl on a dedicated host, avoid installing software on a server. Try to update the stats the night to reduce server impact.

- Logfile

- Local logfile
If you can't run W3Perl on your server, W3Perl can retrieve remote logfiles locally. The remote logfiles should be located in a web directory and password protected of course.

- No logfile access (page tagging) :
From 3.013, you do not need to have logfile access to in order to use W3Perl. Thanks to a small piece of javascript you have to insert in your html pages, logfiles can be generated and so W3Perl can be run.