scenario: you have a sfdc contact id already
you know: that you have a contact, the contact has an owner
in eloqua sfdc update program:
1. make sure you are feeding back a SFDC contact owner id to Eloqua contacts
2. after you run an update contact external call, run a create task external call
3. make sure you map the SFDC Contact Owner Id to the owner id field on the task and any other information you want sent to the contact owner
also note that you probably have tasks being created for form submits that will show up on contacts too, but unless you set something up in salesforce or map a owner id in the external calls for these they will normally be assigned to the eloqua integration user.