Spain Under-21 international Pacheco arrives from Liverpool - where he has made four appearances this season - while Wales forward Vokes joins from Wolves.
The pair are currently away on international duty but will link up with Paul Lambert's squad next week in time to feature against Scunthorpe on April 2.
The Canaries have been keen to add extra firepower to their squad in the final push for promotion to the Premier League and missed out last week on signing Peterborough striker Craig Mackail-Smith.
They have eight games remaining and are nine points behind npower Championship leaders QPR in second place.
Lambert told the club's official website: "The two of them were desperate to come and play and that was very important to me. It will give the whole squad a lift."
Source: PA
Source: PA