Hi,
you need to make some file like modules/CRM/Contacts/soap.php.
This file gets all contacts and companies via webservice... There is also client example in sample_soap_client.php.
You need this PEAR package: http://pear.php.net/package/SOAP
In file with valid epesi initialization you can use all epesi modules common methods...
define('_VALID_ACCESS',true);
define('CID',false);
define('READ_ONLY_SESSION');
require_once('../../../include.php');
ModuleManager::load_modules();
....
...
Paul