David,
Sorry, but it sounds to me like the whole design of this process needs a rethink!
Users should not be logging in as 'test users' (in Production?) to perform specific tasks. Apart from everything else, it usually makes them very upset 
.
The whole idea of an approval workflow is that you let the users do 'something' (eg create a purchase order) and then have their actions subjected to checks and approval.
Or have I misunderstood?
cheers
Paul