Getting action event parameter with ember-gestures and emblem

What I'm trying to do:

Get the event parameter on a panStart and panEnd action, like this:

panStart(event) {
  // do something with the event...
}

Deps:

ember-cli: 2.17.1
ember-cli-emblem: 0.9.0
ember-cli-htmlhandlebars: 2.0.3

various things i've tried

// does something, but as per ember docs this won't give you the event
.item{action 'panStart' on='panStart'}

// these don't work
.item panstart=""
.item onpanstart=""
.item onPanStart=""
.item panStart=""
.item panstart="{action 'panStart'}"
.item onpanstart="{action 'panStart'}"
.item onpanstart={action 'panStart'}
.item panstart="panStart"
.item onpanstart="panStart"

ember docs say to use this syntax for handlebars:

<button onclick=>Sign Up</button>

but there isn't anything in the emblem docs that describe how to translate that