I did a test with Windows Console app
1) Download and unzip binaries
2) Add it as new net runtimes in Xamarin Studio/Monodevelop (i guess there is similar option in VisualStudio)
3) Add references to pscorlib.dll and Playscript.Dynamic.dll
4) Create AS3 file
5) Set its build action to Compile
6) compile
Note, that current version of Xamarin Studio (and I guess monodevelop too) does not have syntax highlight etc