You will just need to create a LoggedInUser instance and after taht you can do everything that you want to do. The below logic will bypass authentication:
'-- Establish Locals
Dim user As New MicroFour.StrataFrame.Security.BusinessObjects.SFSUsersBO()
Dim rbsUser As MicroFour.StrataFrame.Security.LoggedInUser
'-- Populate the BO with the user
user.FillByUserName("MyUserName")
'-- Create the logged in user reference
rbsUser = MicroFour.StrataFrame.Security.LoggedInUser.CreateNew(user)
'-- You can now test on permissions etc. off of the rbsUser