Hi Bruneua,
with some help of support I did the following:
PreExecutionCode:
// Create map array
var attVMArray = new Array();
// Create a single map with attachment fields
var attVM = newValueMap();
attVM.fileURL = Root.NameDestFile; // Process.sdmAttFile;
attVM.contentType = "application/octet-stream"; // Process.sdmContentType;
attVM.contentId = ""; // Process.sdmContentId;
attVMArray.size = 1;
attVMArray[0] = attVM;
// Assign the Map array to a field in Operator
Process[OpName].attachmentMap = attVMArray;
WSDL-Parameters I filled via DynamicParameters
<impl:createAttachment xmlns:impl="http://www.ca.com/UnicenterServicePlus/ServiceDesk">
<sid>sid__</sid>
<repositoryHandle>repositoryHandle__</repositoryHandle>
<objectHandle>objectHandle__</objectHandle>
<description>description__</description>
<fileName>fileName__</fileName>
</impl:createAttachment>
In additional extracted XML-Data I set
xpath:expression: //createAttachmentReturn
DatasetVariable: attachmentHandle
Type: String
Hope that will help.