Hi Silvio,
As far as I'm concerned this is not possible. To minimize the overhead you could create a generic listener, so B1i doesn't retrieve the object XML automaticly (ofcourse filter the events of other objects in the event sender). Then in you scenario step check if the fields you need changed by using the history table. If not drop the process, else continue.
Depending on your needs you could also use the TN to fill a table and use a timer triggerd scenario to read the table.
Hope this helps.
Kinds regards,
Roel van Egmond