Difficult? Very much so? To call it ASB, however, I think, is pushing it. If India, which is more populous and nearly as diverse as Africa, can be united as a single nation, then I think this makes the prospect of a united Africa substantially less ludicrous in comparison. It's twice the size of the largest country, Russia, and has twice as many languages as India, the most diverse nation. I don't think OTL x2 is inherently ASB. So let's give it a shot. I'm pretty sure a POD as late as mine really pushes ASB, though.
1958: In a referendum, all states of French West Africa vote comfortably to remain within the newly-formed French Community, as a unit, with the exception of Guinea, which narrowly votes for independence.
Almost immediately, Sekou Toure takes Guinea into a confederation with Ghana, forming the Ghana-Guinea Union.
1959: Agitation for independence continues, however at this time it is not seen as an inevitable fate; thus a referendum held on whether French West Africa- in its entirety- should become independent, or remain part of the French Community. However this backfires spectacularly and all states overwhelmingly vote for independence. A similar referendum achives a similar result in French Equatorial Africa.
1960: French West Africa becomes independent as the Federation of West Africa under President Leopold Senghor, while French Equatorial Africa becomes independent as the Central African Republic under President Ahmadou Ahidjo.
Meanwhile, Kwame Nkrumah begins to moderate, rejecting the Marxism that had coloured his recent politics and returning to the democratic socialism that marked his earlier years. This facilitates a turn of the Ghana-Guinea Union towards the United States and the rest of the British Commonwealth
The United States pledges its support for the UNOC in the Republic of the Congo, and threatens to break ties with Belgium if it did not withdraw support for the various mutineers and secessionist groups in the Congo, fearing that Patrice Lumumba would otherwise turn to the Soviet Union. Belgium backs down, while the CAR and the FWA are all quick to support the government of Prime Minister Lumumba.
Nigeria, Somalia, and Madagascar become independent.
In South Africa, a proposal to abolish the monarchy is narrowly defeated
1961: Congolese President Kasa-Vubu is forced to resign and is replaced by Antoine Gizenga. The Congo Crisis comes to a close as secessionist forces are gradually marginalized and the government in Leopoldville gains control over the country.