Hi there ... if I remember correctly you have to send Lika a visitor or private message asking to be added. There hasn't been any activity in that group for quite a while now though and I have had other people ask me the same because they couldn't get a response from Lika for that group.
We do have another group for TX going that I help coordinate, but it is not formally associated with the Tejas group so it might not be what you are looking for. Hope that helps