LDAP/ADSI calls without storing username and password

I am looking for away to make calls into LDAP such as

Dim de As New DirectoryEntry("LDAP://Domain.Local","Admin","Password")

If you pass Null strings then it uses the current user account which under IIS is the IIS_USer.

I do not want to give the IIS_User admin rights which would be needed to run this code.

If I run the code in Inpersinate I would be back to storing the account and password in clear text again. I would like to beable to run only this page which I make calls to as the priviliged User. Something Similar to "Run this Program as".

Thanks