IOTL it would be pretty hard, given the diplomatic isolation of Italy. Even then a fact finding mission was sent to Aceh and the far east in 1872-73 (under the cloak of a commercial expedition which made certainly some sense, even if the fact that the commander of this expedition was Nino Bixio gives the impression that there was something more to it). Nino Bixio died of cholera in the bay of Aceh and nothing came out of this idea anymore (although it has been suggested that Italian arm shipments had been sent to Bandar Aceh and were used in the first phase of the Aceh war). The pacification of Aceh was not achieved before 1904, which means that this little bush war lasted all of 30 years (with obvious intervals, but certainly at a huge cost for the government of East Indies). It has also been suggested that the British too provided Aceh with shipments of arms, starting from the first phase (and this I am willing to believe).
It would be quite reasonable to argue that the unsettled situation in west Sumatra offered a lot of opportunities for a power willing to muscle in: the key issue would have been to reach some kind of understanding (probably in the for of a secret treaty or memorandum) sometime in the 1870s: the possibility is there in particular when Gladstone got the premiership (Disraeli was a colder fish and not very much a friend of Italy). One of these occasions might have been the Egyptian crisis of 1876-1882, in particular the British intervention at the end of it (the French pulled out at the last moment and the Italians were invited to participate in their place). Notwithstanding the presence of a significant number of Italian citizens in Alexandria and the economic investments in Egypt Italy refused. It might have gone the other way around, and Aceh might have been a codicil of the joint intervention agreement. The Mahdi revolt in Sudan was another great opportunity to strengthen Italian and British ties but another lost opportunity.
The problem IOTL was the weakness of the governments in Italy, the dissatisfaction with the Italian performance in 1866 and the outcome of the war and the Italian diplomatic isolation.
A stabler government in the 1860s (such as would have been almost guaranteed if Cavour had not died in 1861), a better performance in 1866 (which was not too hard to achieve. Frankly it was OTL performance which was surprising) and a better and more pro-active handling of diplomatic relations (once again Cavour was the man for it) would have significantly changed the trend of Italian history and would have a significant impact on Europe too.
Besides Aceh (which anyway remained a possibility for a long time) there were other opportunities in far east: Sulawesi, Moluccas, Borneo came under Dutch control in the first decade of 1900; New Guinea was another possibility. I will not go into possibilities in Indochina (where the French presence was still pretty limited anyway in the 1860s and 1870s) but certainly a more successful involvement in Southern China was a possibility.
I just had a little brain moment: what if Garibaldi is gently convinced to go to Aceh and fight for its independence? Very much of a stretch I know. But Garibaldi went for other madcap adventures too and this would have been his kind of guerrilla war. Otherwise a surviving Bixio who relinquishes the command of the expedition and goes to fight for Aceh? On the front either of them would fight as a private individual, on the back ....