Check out AutoIt Script. It's a freeware tool that can be used to automate GUI-based applications in Windows. One of the tools that comes with it is the AutoIt Window Info tool. Not sure how close this is to WinSpy, but it should help you find some useful information for the application that you want to automate. It works on my Windows 7 64-bit system.
(NOTE: I'm not advocating that you use AutoIt instead of Win32::GuiTest. Just pointing out that it comes a tool that might be what you're looking for.)