You must use Aspnet_regiis.exe
To use Aspnet_regiis.exe to update a script map for an ASP.NET application
Open a command window. (Click Start, click Run, type cmd, and then click
OK.)
Navigate to the directory of the Aspnet_regiis.exe version you want to use.
Remember that each version of the .NET Framework comes with its own version.
The file is usually located in the following directory:
systemroot\Microsoft.NET\Framework\versionNumber
Use the -s or -sn option of Aspnet_regiis.exe along with the path to the
application to set up the script maps. The following shows a sample command
line that updates the script maps for an application called SampleApp1.
Aspnet_regiis.exe -s W3SVC/1/ROOT/SampleApp1
this is info from :
..NET Framework Developer's Guide
Configuring an ASP.NET Application for an ASP.NET Version