Using MIDI triggered upward compression to make a lead pop

This is a nice effective little trick I watched on Mixbus TV on YouTube. Now all I need is a MIDI triggerable upward compressor, lol...
 

Or easier still, just tweak the synth to have more attack, lol!

Sharke, could this be what you are looking for?
 

Very true. I've a very nice Cajun-style melodeon that clacks quite badly. Close micing makes the problem really obvious, but live it's OK like a humming amp is often OK live. It's recording where the noise becomes objectionable.

I can think of several approaches I'd try first, before resorting to MIDI-controlled expansion. 
 
One of the easiest (but least versatile) is a tempo-synced tremolo. Meldaproduction has a couple of syncable tremolos, with wildly adjustable modulator waveforms. You can, for example, pump the full mix to lend additional rhythmic punctuation. And it's easy to adjust from very subtle to in-yer-face, or to modulate that adjustment via automation. This technique is especially applicable to the scenario described in the video.
 
In the example of a too-soft attack on an sampled instrument, I'd be inclined to solve that by layering. Clone the track and route it to a soft synth, and then design any attack you want. Use a short pluck patch to make your acoustic piano sound like a tack piano, for example. Make the pluck's volume and filter velocity-sensitive so you're only boosting notes that were already accented to begin with. 
 
Going up in complexity, an envelope follower lets you modify any portion of an instrument's envelope. FabFilter Saturn is a great example, as its modulation features are quite extensive. I use it a lot on bass if it needs to be punchier, by modulating both volume and distortion. You can also punch leads up with FabFilter Timeless, or really any delay/reverb that offers a ducking feature. Smudging the release but not the attack has the effect of bringing out the instrument's attack, in the way that dipping one EQ band yields the same result as raising a complementary band. Boz Millar's Imperial Delay is especially good for this.
 
Probably the last resort (next to MIDI-controlled expansion) would be a transient shaper. It's always hit-and-miss with transient designers, but it's easy to stick one in and twiddle its two knobs to see if it's going to work. Multi-band transient shapers can be very cool for pumping up acoustic drum tracks when all you have to work with is pre-mixed audio.
 
But if you really like the technique shown in the video, the Sonitus compressor and Sonitus gate can do it. No need to buy Pro-G.
 

sharke

Soundwise
Sharke, could this be what you are looking for?
 

 

That would do it at a uniform speed though instead of on a per note basis? 

No, you can trigger it via MIDI events. The envelope shape can be adjusted to pump on midi trigger.