Switchmode11 - Anyone know how to correctly implement the functionality?

Hi,

Has anyone perhaps looked at using the free GPIO4 on the Sonoff D1 dimmer as a single momentary switch to control both on/off and dimming? I see Tasmota has a switchmode 11 that supposedly allows for this, but don’t seem to be coming right with both HA and Tasmota config.

My setup is as follows:

1x Sonoff D1 dimmer running Tasmota, with momentary switch connected to GPIO4.
GPIO4 assigned to Switch2 in Tasmota

I have configured Tasmota as per the rule setup below, but nothing happens from there?:

https://tasmota.github.io/docs/Rules/#control-a-dimmer-with-one-switch

Does anyone know the correct way to implement switchmode 11?
Does it require MQTT messaging via HA to work or can it be implemented locally within Tasmota on the dimmer itself?

Any assistance appreciated.