I wouldn´t say the map is ASB. Some ideas for it were floating around 1805-1814. 1805 there were some discussion between Britain and Russia to give Belgum to Prussia if it joins the third coalition. 1814 even Metternich wasn´t very happy with the idea that Austria would have no foothold on the Rhine. Austria wanted Saxony fully restored and Russia wanted all of Posen.
I think a possible POD could be, that Louis Bonapart
http://en.wikipedia.org/wiki/Louis_Bonaparte, Napoleons Brother and disposed King of Holland, who was 1813 in austrian exil, decide to fully switch to the allies side. His support for the Allies and his poularity in the Netherlands is significant enough to get him 1814 rewarded with with becoming King of the Netherland again. But he is still a Bonaparte and the Allies don´t want him to become to strong. So somebody else have to get Belgum and so it goes to the Prussians, who for this have to keep their fingers away from Saxony (at this time still occupied by the Russians) and give Posen to Russia. But the prussian position on the Rhine is so strong, that Austria decide it must also show flag there. So they take Palatinate and let the Bavarians keep Salzburg for it.