Encrypting password in web.config

[session101]

I use a user id and password in my web.config. I do not want the password to be plain text, and would like to encrypt it. I know you can use the ASP.NET_setreg encryption exe to encrypt it in the registry. However, is there a way to input the username and password in my C# .cs file and apss this into the web.config? TIA.