Well...,
Here is how is implemented now (fictive text):
new RunFactory
new Run = RunFactory.addItem(buildRunName)
Run.status(testCaseStatus)
Run.field("RN_HOST",thisHostName)
Run.field("RN_DURATION",duration)
Run.attachments()
[...]
Run.post()
Run.field("RN_EXECUTION_DATE",execDate)
Run.field("RN_EXECUTION_TIME",execTime)
Run.post()
I'm not making a new iteration after all posts, as it would imply some more code to recognize which run is what ( that method works as well, no doubt).
I'm using the same instance to update the date and time. Is true that the first post supposedly should insert a new raw in the DB, but why not allowing custom values for date and time.
Anyway, the solution is elegant enough, only that is not intuitive from my opinion ( the fact that I posted in the forum shows that I spend some good hours fighting )