Hello Georg,
Cesarani indicates two sources to this information and both come from Eichmann himself:
1. Statement made by Adolf Eichmann to the Israel Police prior to his trial in Jerusalem (Interrogation of Adolf Eichmann by Avner Less).
2. Ich, Adolf Eichmann. Ein historischer Zeugenbericht ed. Dr. Rudolf Aschenauer.
Soooo, I'm not sure if we are smarter now...
But even if it's true or not, it was in 1944 not in 1942, because at this time he was in Hungary bored and hanging around in Budapest and our beautiful lake, so called the "Balaton".
By the way, the story seems believable to me, first of all because he had not much to do at that time and second, all the Waffen-SS units were kind of busy with the Soviet Army and the front... So I can immagine that he received a command like this.
Sophie