There are so many "unsupported" devices it would not be possible or practical for 3CX to provide a guide on each, that's why they are unsupported. A number of years ago there were some manual configuration guides, most users want it as easy as possible and may be dealing with hundreds of sets. Some sets have a GUI, so can be manually configured. However, if you are going to do so, it is expected that you have enough knowledge about how SIP works, that you can take the information provided by the PBX, when you create an extension, and use that to datafill a set. For specific sets, there are other sites that may be more specific to the settings. Basically, you'll need the server, extension number and password. Some sets require a bit more.