To install the affiliate script you have to follow these 4 steps:

1) Unzip the zipfile
2) Change in the redirectcounter script the location of $baseurl
3) Copy all the php files to the root of your website. 
4) Make a folder in your images folder called redirect and place the images there
5) Look at your init.inc.php file and search for the following: 

$CONFIG['TABLE_HIT_STATS']  = $CONFIG['TABLE_PREFIX'].'hit_stats';

Add after this :

$CONFIG['TABLE_PARTNERLINKS']  = $CONFIG['TABLE_PREFIX'].'partnerlinks';
$CONFIG['TABLE_PARTNERS']  = $CONFIG['TABLE_PREFIX'].'partners';

6) Add to your database the following (change the cpg143_ for your own table prefix)

CREATE TABLE `cpg143_partnerlinks` (
  `linkid` int(11) NOT NULL auto_increment,
  `urladres` varchar(255) collate latin1_general_ci NOT NULL default '',
  `urlname` varchar(255) collate latin1_general_ci NOT NULL default '',
  `counter` int(11) NOT NULL default '0',
  `since` date NOT NULL default '0000-00-00',
  PRIMARY KEY  (`linkid`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci PACK_KEYS=0;


CREATE TABLE `cpg143_partners` (
  `number` int(11) NOT NULL auto_increment,
  `partnerid` int(11) NOT NULL default '0',
  `linkid` int(11) NOT NULL default '0',
  `remove` char(3) collate latin1_general_ci NOT NULL default '',
  `edit` char(3) collate latin1_general_ci NOT NULL default '',
  `reset` char(3) collate latin1_general_ci NOT NULL default '',
  PRIMARY KEY  (`number`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci PACK_KEYS=0;


7) Add a link in your theme to the file or just visit it directly.

Any comments welcome at the coppermine board topic:
http://coppermine-gallery.net/forum/index.php?topic=29920.0
 