If you want to look at commands supported by any windbg extensions, you can follow various ways.

• You can use !<ext_name>.help command to see all the commands supported by that extension. Replace <ext_name> with your extension module name. (Note: This will only work if particular extension supports help command.)
• You can open the extension DLL in Dependency Walker and it will show all the command in exported function panel! There is no magic behind it, its merely a fact that WinDbg has very simple extension model, where you need to implement exported function for each command. Windbg just does GetProcAddress for that function and call into that, when we use that debugger extension command in Windbg. And dependency walker has functionality to show exported function from a module.
  

Stay tuned..