A money manager who defrauds his client by convincing debtors to defraud the master by cooking the books may be shrewd and using his noggin.
Unfortunately, I consider these to be dishonorable and unrighteous actions that I personally will not commit. I think that you need a different parable.
But Jesus sometimes makes this sort of comparison, from lesser to greater. If an unjust judge will hear the plea of the importunate widow, how much more will your heavenly Father hear your prayer. If you fathers, though you are evil, know how to give good gifts to your children, how much more will your heavenly Father give good gifts to you. That sort of thing.
1. The steward was "unjust" for whatever reason he was being terminated by the master (i.e., "wasting his possessions").
2. The steward was "unjust" because his manipulation of the records was defrauding the master of property that rightly belonged to him.
3. The steward had been "unjust" in his prior dealings with the master's debtors -- perhaps by collecting more from them in the past than he was reporting to the master.
Item #2 is the most common interpretation of this parable, but I think this is the least likely of the three scenarios I've listed. The reason for this is three-fold: (A) because it's unlikely that Jesus Christ would tell a parable where someone was to be commended for theft; (B) someone in the master's position isn't likely to commend an employee who has stolen from him; and (C) because this makes not only the steward unjust, but the debtors as well (and yet they're never described in a way that makes them seem like co-conspirators in a crime).
Another important consideration comes after the parable as it was told in Luke 16:
Now the Pharisees, who were covetous, heard all these things: and they derided him.
Why would the Pharisees deride Jesus Christ over this particular parable?