Sorry I haven't seen this yet- been quite busy as of late

Really, all you need to set up a gamemode-specific module for XGUI is to create a file in your gamemode or addon's lua/ulx/xgui/gamemodes/ folder, and name it the EXACT same name as the folder name of the gamemode you want to use. (Likely ttt.lua).
The "magic" for this happens here, if you want to see how XGUI loads it.From there, the only required thing you have to do is have these two lines of code in your ttt.lua file:
local nameofyourpanel = xlib.makepanel{ parent=xgui.null }
-- Your code to create the UI here
xgui.addSettingModule( "TTT", nameofyourpanel, "icon16/box.png", "xgui_gmsettings" )
.. Where "nameofyourpanel" will be a oddly sized panel you can affix Derma elements to, "TTT" is the text that appears on the tab, "icon16/box.png" is the icon that shows on your tab, and "xgui_gmsettings" is your required permissions level to be able to access it.
That's it!
How you go about creating your list of CVars is entirely up to you- you could copy what I did with the sandbox settings, but it pulls in lists of limits from a file that's stored on the sever (
the serverside code for that is here). Feel free to ask more questions- I will try to respond as quickly as possible
