The sample "setup_2.cs" yields wxs very similar to yours. It is not included into release so you need to download it from codeplex:
https://wixsharp.codeplex.com/SourceControl/latest#src/WixSharp.Samples/Wix# Samples/IIS/ASP.NETApp/setup_2.cs
Drop the file into your [Wix# Samples]/IIS/ASP.NETApp folder and you will be able to execute it.
https://wixsharp.codeplex.com/SourceControl/latest#src/WixSharp.Samples/Wix# Samples/IIS/ASP.NETApp/setup_2.cs
Drop the file into your [Wix# Samples]/IIS/ASP.NETApp folder and you will be able to execute it.