Have Mussolini accept the Anglo-French proposal of gaining Djibouti and trade rights in Tunisia in exchange for not invading Ethiopia.
Couple of years later, the British, in desperate need of italian support in some european crisis involving the nazis, accept to sell british somaliland to the italians in return for their support. The nazis back down over the issue, only to push for it again later and find an inexistent allied response. This convinces the Mussolini that the Allies are weak and also that Hitler will have no problem backstabbing him should he feel like it, and so decides to pursue a neutral strategy.
Albania is made into a puppet state as OTL.
Once war breaks out between Germany and the Allies, Mussolini goes for Yugoslavia, using the existing interethnic tensions to his advantage. The war drags on for a bit, until Bulgaria and Hungary opportunistically intervene on the Italian side. A peace agreement is reached, whereby Budapest and Sofia each get a small slice of territory, Italy directly gains some coastal regions and Croatia and Montenogro are created as Italian puppets.
Towards the end of the war, Italy agrees to join the allies in return for lend-lease, lots of cash and cheap loans, an acknowledgement of their territorial gains and a promise that Ethiopia will be in their sphere of influence. Allied victory in late 1944.
Years after the war, Mussolini uses some excuse to cause a civil war in Ethiopia and, supporting this and that faction, successfully pupetizes the place. While western countries don't really agree with it, images of Ethiopians cheering parading Italian soldiers in the capital Addis Abba (like happened OTL), as well as the need to contain communism in the Balkans, mean western governments turn a blind eye to the whole thing.
As a bonus, have the Greek communists win on the mainland, with the rest of (monarchist) Greece restricted to only its island possessions and increasingly reliant on Italian military and economic aid.
Other than maybe also an occupation zone in post-war germany, i think this as the most you're going to realistically get, and even this is stretching it.
