Adding a specific user to the app pool identity

[develo...@gmail.com]

I have an app pool, but I don't know how to add my specific user along with the password other than to go into inetmgr manually and set it.

Suppose I have a user "MYDOMAIN\someuser" with password "somepassword".   How can I add these credentials in for the identity.  This is what I have so far, but I just need the part where it takes the user credentials.  I don't even mind if the password is stored or I'm prompted to enter the password.  Has anyone accomplished this successfully?

let appPoolConfig = ApplicationPoolConfig(appPoolName, allow32on64 = is32Bit, identity = Microsoft.Web.Administration.ProcessModelIdentityType.SpecificUser)