IMHO you can only join the network if your unit uses the KIT1 firmware for a DIY device.
I think the effort to convert a unit to be KIT1-like with all the pins and display and stuff is too much trouble.
Well, indeed, the KIT1 is the starting point here, but you can use its mechanism with any detector you have or build. What this means is that you can look at the way the KIT1 uploads the data (via the EXP protocol) and implement that for your device. https://github.com/radhoo/uradmonitor_kit1