Following are the step to install Silverlight 4 for Visual Studio 2010 RC
- Download Silverlight 4 for VS 2010 RC
- Start the installation
- you will see the error message as shown in below Figure 1.1
Figure 1.1

- Do not click the close button
- on open your installed window drive e.g c: drive
- New Guid genrated folder
- copy entrie folder with name SL4
- Now, open SL4 Folder
- Open ParameterInfo.xml file
- comment on the line 13 to 41. <!- ALL ->
- Start SPInstaller.exe
- open your regedit
- Open the following key
- HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ VisualStudio \ 10.0 \ DesignerPlatforms \ Silverlight]
- Change the value "SilverlightHost" to "v4.0"