1st. Take a look at the tasmota issues
2nd. More info then you need here:
It works for the 4ch version too. It works on the Dual version
and on the 4ch like a charm.
Ok you have to solder things togehter but that's the only way.
Read, read, read. That's all the help we can give you.
As an addition to your question:
- there is NO easy way to solve it because the hardware was never made for it.