How to trigger a Virus in its Multi mode from pattern mode?
 

In Pattern Mode on Motif, there are two areas: Pattern Mode which deals with the pattern sequencer tracks and Mix mode which deals with the Motif's internal tone generator.

The Motif's pattern sequencer is set so that Track 1=MIDI channel 1, Track 2 = MIDI channel 2, etc. You should be able to set the Virus to say receive on channels 1-4 and then use the Track select on Motif to select Tracks 1-4 and hear the different Virus sounds.

To call up different sounds, you can insert the correct Virus program changes into sequence data. If you don't want to layer the Virus and Motif internal sounds on MIDI channels 1-4, go to MIX edit, press 1, then F1 Voice, SF2 Mode and set the Motif Parts 1-4 MIDI receive channel parameter to OFF. Then you will hear only the Virus being played by the data on MIDI channels 1-4 of the pattern sequencer.