Not at all. You can use any program that will record audio files (a community favourite is Audacity; easy to use and freely available, which is a bonus).
All you have to remember is to record the voices in WAV or OGG format (as these are the only two formats the game engine recognises), stick them in your Movie Sound directory then (when in Post Production in the game), click on the voice track, navigate to where you put them and select the track. Once it's positioned, right click on it to assign it to an actor.
It's not recommended that you use voice tracks of longer than 14 seconds or so for each piece, as the game struggles to lip synch correctly with anything over this length. You also need to ensure you break your dialogue up into individual lines, as you can't synch one long file to multiple characters.
Machinima maker? Using The Movies? iClone? Moviestorm? Any other engine? Then check out TMUnderground at (http://www.tmunderground.com/)