Is there a way to do this in Cubase Artist 6 ?
You could use the Transformer to output random velocities.
Hi, 
It would make sense to outline the situation and usecase you are facing a little bit more so we can give you more specific advice.
Anyway, try and see if this works for you:
In the second gif (Some_Volume_Changes_MIDI Inserts_Merge_MIDI_In_Loop.gif)
in my “MIDI Velocity Editing. Awesomeness!!!” thread you can see how I use a MIDI insert compressor and merge the effect into the MIDI data. Instead of the MIDI compressor you must use the “MIDI Modifier” insert. Then set it up to randomize the velocities of the notes as exemplified in my attached png (Random Velocity–> -50 +50):
If you would like to merge the effect with the MIDI data in the event you can either use the “MIDI-> Merge MIDI In Loop” function or also the “MIDI->Freeze MIDI” modifiers function.
Maybe you would like to share with us why you would like to randomize velocities. Are you planning to make drums less static? Which VSTi are you using in conjunction with that MIDI track?
Gr,
JHP