The world number five beat fellow Spaniard Fernando Verdasco 6-3 6-4 in the semi-finals while Rochus, ranked 68, knocked out 2008 champion Philipp Kohlschreiber 6-7 (4-7) 6-1 6-4.
It was a busy day for both players who played their quarter-final matches as well as their last-four games after rain had wreaked havoc on Thursday's schedule.
Both were taken to three sets with Ferrer beating Alejandro Falla 6-4 4-6 6-3 while Rochus withstood 21 aces before edging out Benoit Paire 6-3 6-7 (5-7) 7-6 (7-4).
Against Verdasco, top seed Ferrer created 12 break-point opportunities and was able to convert one in each set to claim victory in 89 minutes.
Should the 29-year-old triumph on Saturday it will be the third time he lifts the Auckland title after having also been crowned champion in 2007.
Rochus converted six of his nine break point opportunities against Kohlschreiber to take the semi-final clash in two hours and 28 minutes.
The Belgian is looking for his third ATP World Tour title, his last coming in 2006 at the BMW Open in Munich.
"I'll just try and enjoy the final and go for it," Rochus is quoted as saying on the ATP website.
"There's no pressure for me; I will play against one of the best players in the world in a final of an ATP event. This is why we practise, to get the chance to play these kinds of matches."