[Артем Enot Грунин]

Изменить владельца лучше не через Workflow. Лукап можно заполнить скриптом: читайте SDK:

//Create an array to set as the DataValue for the lookup control.
var lookupData = new Array();
//Create an Object add to the array.
   var lookupItem= new Object();
//Set the id, typename, and name properties to the object.
   lookupItem.id = '{1AAC1363-01A1-DB11-8432-0003FF9CE217}';
   lookupItem.typename = 'account';
   lookupItem.name = 'A Bike Store';
// Add the object to the array.
   lookupData[0] = lookupItem;
// Set the value of the lookup field to the value of the array.
   crmForm.all.parentaccountid.DataValue = lookupData;