Codes for Gelia EMW203R 433MHz

So I’m quite new to Home assistant. In my old house I used Domoticz but then mostly for logging.

Started up a Pi with Hassbian the other day to start checking for supported hardware and so on.
IKEA trådfri, Verisure home alarm, TV and more seems to work nicely.
Yesterday I found my old 433MHz RfxTrXCOM and a couple of outlets that would be nice to complement the installation with.

I receive tempsensors from all around and also managed to add a switch to control some recievers.

Then I have some Gelia outlets, EMW203R, but I lost the remote when moving from my old house.
They have a channel selector on the back with A,B,C,D and 1,2,3 for each.
Since I don’t have the remote I can’t take the “easy” way of receiving the codes and then adding them.

Anyone have some guidance for how to figure out a way to use these with my Home assistant?