File watchers to minify and merge JS files from multiple folders

I am trying to acomplish the following.

I have raw assets such as javacript source files in folder assets/js in aplication root. I also have folder public where should go minified files that will be loaded in application.

What i want is when i change my js files i want to IDE create minified versions of it, and then to merge those minified files into one in public folder.

I need two file watchers but don't know how to configure them.

I tried default options for YUI compressor and those build minified files in the same folder where source files are. But i can't manage to merge those files with file watcher.

I also created two scopes, one for souce JS files, and one for minified JS files.

I am not even sure. file watchers can do this. I am talking about multiple folders, and recursive scopes.

I would appreciate any help.