There was a discussion of this a while ago on TDM's forum, and Loz mentioned a "house ruling" that he has used; key points:
- If there's an alternative Standard skill available (such as Influence instead of Oratory), then you can substitute that at the Hard grade of difficulty.
- If you want to attempt an untrained Professional skill, then the chance of success is at its base characteristics, and at Hard difficulty.
- Also bear in mind another rule: any roll of 05 or less is a success. This is irrespective of any skill and could, in theory and as the rules stand, be applied in these circumstances.