Is the velocity automateable? I cannot find it in instrument automation device and midi control device. Thanks.
You can enter velocity into the volume columns in pattern editor. Velocity isn’t more automatable than that anyway, as you know it’s send only on note triggering.
You should be able to use midi aftertouch to automate volume if the vsti supports it.
Well, that’s exactly what I don’t want. I would like to control the velocity by using a LFO for example. 
- Figure out which parameter velocity is actually mapped to in the VST/AU synth.
- Connect your Instrument Automation device to that synth and parameter.
- Connect your LFO to the Instrument Automation device.
- Profit.
Ok, but would be much more easy to directly control velocity, since it’s a common parameter to modulate. So I have to patch the preset all the time.
Yes, it could be nice for the future, but I was simply trying to give you a solution that works right now 
Some “Override Velocity” fader in midi control metadevice would be awesome.
Or even better a pattern command meta device as I suggested now here.
You do understand the relationship between the Velocity column and polyphonic aftertouch in Renoise don’t you?
This is not stupid idea because velocity is per note, this is a great idea because of that.
Examples:
If velocity could be modulated we could use lfo as dynamic humanizing device! Even better if there would be note range it affects, so we could have for example snares and claps affected by one velocity automation device and kick drum by other.
We wouldn’t even need to ditch the old velocity values - it would be possible to combine random lfo and volume column with Velocity Tracker (which is incorrectly named and actually volume column value tracker) and Meta Mixer.
If we use automation device to control parameters controlled by velocity the results will be different than controlling velocity which controls the values. This is why dblues suggestion isn’t same thing at all. For example modulating attack with automation device affects ADSR curves of all notes currently playing, but using synths builtin modulation system to modulate attack with velocity will affect only attack of note starting at that point.
Assuming the synth itself actually provides a unique ADSR envelope for each voice in the first place, otherwise any change to the ADSR will affect all voices regardless.
But you’re quite right; my suggestion is not the same thing, nor did I claim that it was. I’m definitely not trying to shoot down this feature request, either. It would indeed be very interesting to allow the velocity to be modulated, so that when new notes do get triggered, they get triggered with the modulated velocity.
More control over things always get a +1 from me.