In this video, I show how to use an external, standalone instance of Reaktor to control instruments in Maschine. Due to limitations in the Maschine software, this is not possible in Maschine alone.
This Maschine tutorial uses LoopMIDI, a free program for creating virtual MIDI ports. You can download it here.
Unfortunately, LoopMIDI is a Windows only solution. If any Apple users know of something similar for OS X, please let us know in the comments.