Calderon said that negotiations are continuing as he seeks to renew the Spanish powerhouse's squad.
"We've been working on new signings for the last three months," Calderon said in Tuesday's edition of Sports daily As. "Metzelder is signed up and there are three more who are almost done."
In May, Kaka's Brazil teammate, Robinho, said the Milan midfielder would like to move to Madrid, but that it is unlikely the Serie A club would agree to release him. Kaka is contracted to Milan until 2011.
"We all know that Kaka will have to force his exit from Milan, and I continue to believe that he will try," Calderon said.
Kaka set up Filippo Inzaghi's second goal as AC Milan beat Liverpool 2-1 in the Champions League final in May. Milan became European champion for a seventh time - two less than Madrid's record nine.
Kaka scored a tournament-high 10 goals during the Champions League this season.
Calderon pledged to sign Kaka as part of his campaign for the presidency last year, but Milan has repeatedly said it has no intention of releasing him.
In July, Calderon wrote a conciliatory letter to Milan vice president Adriano Galliani, who had called Madrid's management "bandits" for trying to sign Kaka while he is still under contract to the Rossoneri.
In April, Ronaldo signed a five-year extension to his contract at Man United through to 2012.