Is There A Way To Do Really Fast/accurate Volume Automation?

Less ghetto in execution style, more ghetto in result, but still not the real thing:

I use an instrument to trigger the compressor directly. The trigger instrument is a wild DC offset which gets cancelled by Renoise’s not-so-precise Filter2 (well, two of them). If you have a better VST filter, the result will sound better (crisper cutoff=less compensation for bass loss in the EQ).

Get it here.

So now instead of typing in effects laboriously, you can just use the “ducker” instrument… still not ideal, but the principle is good if you can get a very fine-grained filter.