Not quite. Metternich's goal was to create a stable Europe where status quo could be maintained (and Austria's position) with no Great Power too powerful. Considering the amount of land exchanges that happened at the Congress, he had little interest in completely pulling the clock back completely.
Speaking of Metternich, one of his failed project was to introduce an 'Italian League' modeled after his German Confederation, but the monarchs of the region refused.
So, I can think of two ideas and they both involve Leopold II of Tuscany:
1) The Italian League is founded, bringing the Italian states a little bit closer earlier. Some kind of Zollverein may happen as well later on. When Vienna is distracted by Prussians or angry Liberals, their power erodes in Italy and Leopold II takes the reins. Eventually, the Italian states are united by Tuscany instead of Sardinia. After all, Leopold sympathised with the Italian nationalists and was well-liked before Vienna forced his hands after 1848.
2) Leopold, as per OTL, supports the revolutionaries in Milan, although perhaps even more. Somehow, the Austrians are less succesful (perhaps their distractions are more severe elsewhere and Radetzky is sent elsewhere). Leopold then secures leadership of the Italian revolutionaries (perhaps by telling Vienna that a Italian Habsburg is better for them than Vienna herself or, worse, a Savoyard). Either the Savoyards hesitate to take advantage of the situation or Leopold beats them.
Either way, I think Leopold is the only choice, but his credibility was destroyed by, ironically, the Austrian victory.
Of course, number 2 can happen with PoD 1, but the first one can have more severe butterflies by the time 1848 hits.
