To answer the first question, I believe it is impossible, but would be far more work than it would be worth.
To answer the second question, it honestly depends. The bigger the mod is, the greater chance of incompatibility. With total conversion mods, they are so great in their reach that so many effects can be changed.
As of 3/14/10, TSL is restored. The Sith Lords Restored Content Modification by Stoney and Zbyl has been finished and can be downloaded here