Well, I had to get a Linux machine setup to get it compiled. I'm not a Linux guru, so that's probably what was the most difficult thing. But I know a little C++.
I'm just using the CLI app after I got it compiled. I wrote a small Python script that listens to web requests and then calls the command line to analyze the plate image.
You can download it from GitHub https://github.com/openalpr/openalpr
You need "git" installed to download it.
I'm not sure if it will run on Windows... I haven't tried it.