Extract uniSWF/Snapshots/uniswfSourceLatest.zip outside of the unity project Assets/ folder.
Copy the latest UnityEngine.dll & UnityEditor.dll from the unity install path to dependencies/4.0.1f2 for Unity 4 and dependencies/5.0.0b14 for Unity 5.
OSX Location: Right click on the unity application and 'Show Package Contents', navivate to Contents/Framework/Managed/
Windows Location: C:/Program Files(x86)/Unity/Editor/Data/Managed/
Open LibUniSWFEditor/LibUniSWFEditor.sln in Mono Develop on OSX or Xamarin Studio on Windows. Please note the version of Mono Develop on Windows differs from the Mac version so use either Xamarin studio or Visual studio.
Update .Net References to UnityEngine.Dll & UnityEditor.dll in all sub projects if needed.
Set the active target to ReleasePro.
Clean build.
Build all.
Copy dlls located in bin/ReleasePro to uniswf/DLLs & uniswf/DLLs/Editor to the relevant unity projector folder.