Associative Array with WSDL

I'm trying to get an associative Array through SOAP using the 0.7.5 SOAP_WSDL Class. The server dispatch map for the used function simply contains 'out' => array('foolist'=>'object') The foolist object has an associative array, the indizes are integer values, but not enumerated. An array with indizes '1','5','6' looks like '0','1','2' after going through SOAP, and only the index '1' contains valid data. How can I properly use an associative Array? Do I have to specify the dispatch map more in detail (how)?