Yeah, it works great. I connected the wires to a relay module, in NO mode, which is inverted whithin the home assistant configuration. The advantage is that, whenever the system crashes for whatever reason, the TELE setting will be turned off.
I found this image on the web of the backplate:
Source: Chronotherm IV vervangen door Chronotherm Touch | Honeywell Home - YouTube
And this one of the Chronotherm Touch:
Source: Thermostaat vervangen: Chronotherm III | Honeywell Home - YouTube
I can’t take a picture of my parents situation right now. The picture of the Chronotherm IV above is slightly different of the situation on my parents thermostat. They have a Chronotherm Modulation (uses OpenTherm). Which is different from Chronotherm IV (uses on/off). As you can see, there are two wires connected for signalling to the boiler. The backplate of the Chronotherm Modulation has more extra screws to attach more wires. I cannot tell you to which screws the wires should be attached at. I believed they were called TE, which you also see on the Chronotherm Touch picture.
It can depend from within the product range of the chronotherm if the TELE setting is available. The article on Bedien je verwarming op afstand – TD-er says a lot of Honeywell chronotherm thermostat after 1999 have it.