Set up a service account to run application pool

a) Give "Logon as a service" and "Logon as a batch job" permissions to the newly created service account.

Note: If you don't give the above permissions, the application pool will crash.

b) Run the following command

aspnet_regiis -ga \AccountName

The above command with -ga switch grants the following rights to the account:
1. Access to the IIS Metabase

2. Permission to write to the %Windir%\Microsoft.NET\Framework\version\Temporary ASP.NET Files folder