You only need to press Ctrl+~ to activate the zoom window, assuming that Aero is enabled.

To change the hot key that activates the zoom window, you can go to the file LiveZoom.cpp (currently, on line 85), and change the last parameter to the RegisterHotKey function. It is currently set to 0xC0 which is the the code for the tilda key on US keyboards.

// Register hot-key
if (!RegisterHotKey(hWnd, HOT_KEY_ID, MOD_CONTROL, 0xC0))
   SendMessage(hWnd, WM_DESTROY, 0, 0);

You can set to something like 0x31 which is the code for the
For more key codes, you can look on this page:

When I have some free time, I might update the app with a Settings window and some performance improvements.