I contacted the developer of AllSnap to see if he would give me the code so I could fix it, but he is ignoring me. I can tell from debugging apps when AllSnap is installed that it seems to work by injecting a DLL. This is similar to how I hacked the poker sites for GoldBullion, so I think I could probably reproduce that. But I dunno if Win7/x64 has changed anything about function injection and the whole DLL function pointer remap method.
BTW/FYI the standard Windows function injection method goes like this : Make a DLL that has some event handler. Run a little app that causes that event to trip inside the app you want to hijack. Your DLL is now invoked in that app's process to handle that event. Now you are running in that process so you can do anything you want - in particular you can find the function table to any of their DLL's, such as user32.dll, and stuff your own function pointer into that memory. Now when the app makes normal function calls, they go through your DLL.