Change User of CSP Session

Is there a way, for testing purposes at least, to change a CSP session over to a different user? We have a lot of things in our system that are allowed or restricted based on the user login, so it would be useful for me to be able to occasionally run as a different user to see how things look and work for them. I've tried using the %CSP.Session.Login function, but that still shows the CSP session as being from the original user, not the one I've switched to.