I'll try to stick to the spirit of your question; but I ask for a bit of lenience, for I want to give at least a small overview of the events surrounding the week and most of the things Mussolini did during his first week of power were setting up events happening throughout the late 1922 early 1923.

 

Mussolini was appointed Presidente del Consiglio on October 28 1922 in a legal fashion. Talks of institutionalizing Fascism, by involving its leaders in the parliamentary business, had been going on for a while, most likely by the creation of a Giolitti-Mussolini Ministry where Mussolini would have held the Ministry of Internal Affairs. Late during the month of October a possibility for a Facta-Mussolini Government^1 seemed to develop as testified by the exchange on October 26th 1922 between Facta and the King:

 

Mussolini made me aware that he would join Ministry if led by me. Also requires ministries with expenditure power.

 

And the King's answer:

 

The only way to avoid dangerous shakes is to involve Fascism into the Government through legal ways.

 

In this situation, Mussolini was playing on two tables: on one hand he was treating with the Government and the Crown for a political solution^2 , gaining time for his “revolution”; on the other he was arranging a mostly demonstrative action with the other movement leaders, waiting for the right time to push against the unstable Facta Ministry.

The amount of telegrams, phone calls, private colloquies that took place in the last days of October 1922 is difficult to summarize and it would be difficult to follow.

In short: Mussolini wanted a Fascist Government, i.e. a government led by a fascist Prime Minister with relevant fascist ministries. To accomplish this his purpose was to stage a mostly non violent nationwide demonstrative action, weighting his odds on the fact that the Government would be unable to suppress it and that this would lead to the Ministry's fall and the King appointing Mussolini himself as new Prime Minister.

His prediction was right.

Facta, at first Giolitti's placeholder and then to be replaced by Salandra, was often blindsided by the events of those days and believed at least to the late afternoon of the 27th that he could be the man to find an agreement with Mussolini and bring the fascists into his Government.

His plan was simple: let the “march” begin. Ask the King for the power to declare the state of siege. Witness the fascists run away in front of the army – a very likely event, despite the fascist proclamations – and find, if still necessary, an agreement with a now much more amenable Mussolini.

Yet to his surprise, on the morning of the 28th the King refused his request, leaving to him the only choice to offer his resignation.

In sight of the refusal to use the Army to stop the fascists, no realistic alternative was left outside of a Mussolini Government. And soon the establishment, the press and the political world came to the same conclusion^3.

Nonetheless a last attempt was made to form a government led by Salandra. But Mussolini was now confident in his chances of establishing his Ministry. His answer to an informal phone inquiry the night of the 28th was that he would have rather worked with Giolitti than Salandra^4 ! On the morning of October 29th De Vecchi, Ciano and Grandi went back to Salandra with the official answer of Mussolini.

Salandra had no choice but to decline the appointment.

Faced with the situation, the King asked De Vecchi to ask Mussolini to come to Rome – Mussolini had avoided being in the middle of the action, in case things took a turn for the worse. Mussolini replied asking for an “official” confirmation telegram.

After he obtained it, he left for Rome at 8.30 pm and arrived only at 10.50 am on the 30th – a delay caused by the fascists themselves.

He went to meet the King, from 11.15 to 12.00, where he ensured Victor Emmanuel III that he would have a list of ministries ready by that night.

 

In the late afternoon of the 30th Mussolini submitted to the King his list of Ministries. Mussolini held for himself the Internal and Foreign chairs while appointing moderate fascists at Finance (De Stefani), Justice (Oviglio) and Freed Lands (Guerzoni). Two memebers of the Partito Popolare (Catholics) were included; two military men held the ministries of War (Diaz) and Navy (Thaon de Revel); the nationalist Federzoni (who had wanted the Internal Affairs) held the Ministry of the Colonies); the philosopher Giovanni Gentile was installed at the Education chair.