I need to return M-Files user by using calculated value (VBScript)

I will utilize a connection to an external database to manage the employee object. This employee object includes a property for storing the email address, which I want to use to search for the corresponding M-Files user account. Once the user account is retrieved, I want to update the "M-Files User" property in the employee object. The "M-Files User" property is a dropdown list that allows selection from the Users value list.  Could you please to share me some script sample? Thanks.