In a statement released on Saturday, the rebel group said that it had already begun the handover process.
"We hope that the weather will be on our side on this humanitarian mission," the Farc said.
Gen Alzate's abduction on 16 September prompted President Juan Manuel Santos to suspend peace talks with the rebels being held in Cuba.
He was captured along with Cpl Jorge Rodriguez and a lawyer, Gloria Urrego, in Choco province, an isolated jungle region in Colombia's Pacific Coast.
On Tuesday, the Farc released two soldiers - Paulo Cesar Rivera and Jonathan Andres Diaz - it had kidnapped on 9 November in the eastern border region of Arauca.
Mr Santos had said that he expected Gen Alzate and the two other hostages to be freed earlier in the week.
But the Farc cancelled the operation, blaming "heavy military presence" in the region where the hostages are being held for the decision.
On Saturday, the rebel group announced in Havana that the "special humanitarian protocol" to free the three hostages had already been activated.
The protocol is well known in Colombia from the release of previous Farc hostages.
Usually, the Farc gives the government the co-ordinates for the handover point.
The Colombian president orders military activities in the area to cease for a short period of time - no longer than 48 hours.
The hostages are then handed over to the Red Cross, which does a quick health check before taking them to safety elsewhere.
The hostages undergo further health tests and are debriefed before being allowed to meet their relatives.
The left-wing rebel group also called on the government to be inspired by its decision to release its hostages.
"We wish that other prisoners, arrested for political or social reasons, are also able to enjoy their freedom. That would be an easy, humanitarian gesture from the government," says the statement released in Havana.
The Farc said previously that it kidnapped Gen Alzate because it was unhappy at the continuation of Colombian military activities during peace talks.
It had called for a ceasefire, but this was rejected by the government.
Mr Santos has suspended the peace talks, which began two years ago in Cuba, and said they would only be resumed once Gen Alzate was released.
The negotiations are aimed at ending five decades of a conflict that has killed an estimated 220,000 people.
Farc rebels in Colombia are expected to release Gen Ruben Dario Alzate and two other hostages later on Sunday.