Hi Daniela,
I unfortunately cannot disclose all the details, but Artefactual did complete a project for a client recently to support a very basic Preservica AtoM integration. Getting it to work involved some internal code changes that will be included in the upcoming 2.7 release, but also additional custom code changes made locally to support the specific client requirements, which will not be included in a public release.
Consequently, while it can be done, and while 2.7 will make it easier to set up, at this time there's no easy way to establish a Preservica - AtoM integration without further custom development.
I was hoping that by delaying I would be able to say more, but at this time no further details are forthcoming.
Regards,