I spent almost 3 hours attempting to do this for the first time yesterday evening so I figured i'd post what i learned to speed up the process for anyone else attempting to do it.
* I'm assuming that you have some basic understanding of Girder and Xlobby, if not, this probably wont help you much. *
First things first! Go to girder and copy ‘gireventlib.dll’ into your xlobby directory. (Anywhere in the windows path should do.) If you don’t have this, xlobby will throw an exception every time you try to communicate with Girder.
Second. Go into girder and build your command or command group. Get it working within girder and test it just to emanate that as being a variable.
Once you’re happy with the command do ‘add eventstring’ under the new command. Near the top center of the event configuration screen change that drop down item from ‘all’ to ‘girder event’ and then press ‘learn event’ that will pop up a small dialog window which will let you key in a name for your event. This name is how you can launch the event from girder.
Now go into xlobby and create a new button. Once you create the button and assign a graphic to it, go to the ‘Girder Event Strings’ tab for that new button and in the big text area simply type in the name that you gave to you event in the earlier step.
If you got things just right, pressing that button in xlobby should cause the girder event to execute.
Optional:
If you’re having problems and want to test your ‘event string’ outside of xlobby, open a command window and go to the girder directory. Now with girder running in the system tray execute:
girder.exe -eventstring myEvent
Where "myEvent" is the name that you gave to your event in girder.
I hope this helps.
Good luck.